diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
index 3d5f73a6da1..de38d9771ae 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
@@ -408,6 +408,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE) { firDiagnostic ->
+        DuplicateParameterNameInFunctionTypeImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS) { firDiagnostic ->
         CreatingAnInstanceOfAbstractClassImpl(
             firDiagnostic as KtPsiDiagnostic,
diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
index dc2144bbaa3..d89bc3fb1f7 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
@@ -331,6 +331,10 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         val reference: String
     }
 
+    interface DuplicateParameterNameInFunctionType : KtFirDiagnostic<KtTypeReference> {
+        override val diagnosticClass get() = DuplicateParameterNameInFunctionType::class
+    }
+
     interface CreatingAnInstanceOfAbstractClass : KtFirDiagnostic<KtExpression> {
         override val diagnosticClass get() = CreatingAnInstanceOfAbstractClass::class
     }
diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
index c8c19d508d8..c6b68fd7f2a 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
@@ -381,6 +381,11 @@ internal class UnresolvedImportImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.UnresolvedImport
 
+internal class DuplicateParameterNameInFunctionTypeImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtTypeReference>(firDiagnostic, token), KtFirDiagnostic.DuplicateParameterNameInFunctionType
+
 internal class CreatingAnInstanceOfAbstractClassImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,
diff --git a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
index c4d17377f5f..b8192555a51 100644
--- a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
+++ b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
@@ -174,6 +174,8 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val UNRESOLVED_IMPORT by error<PsiElement>(PositioningStrategy.IMPORT_LAST_NAME) {
             parameter<String>("reference")
         }
+
+        val DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE by error<KtTypeReference>()
     }
 
     val CALL_RESOLUTION by object : DiagnosticGroup("Call resolution") {
diff --git a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
index 2270817803b..4893f9c5678 100644
--- a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
+++ b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
@@ -172,6 +172,7 @@ object FirErrors {
     val API_NOT_AVAILABLE by error2<PsiElement, ApiVersion, ApiVersion>(SourceElementPositioningStrategies.SELECTOR_BY_QUALIFIED)
     val UNRESOLVED_REFERENCE_WRONG_RECEIVER by error1<PsiElement, Collection<FirBasedSymbol<*>>>()
     val UNRESOLVED_IMPORT by error1<PsiElement, String>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
+    val DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE by error0<KtTypeReference>()
 
     // Call resolution
     val CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS by error0<KtExpression>()
diff --git a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt
index 27a6ac623ea..8c499c24c9b 100644
--- a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt
+++ b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt
@@ -52,6 +52,7 @@ val FIR_NON_SUPPRESSIBLE_ERROR_NAMES: Set<String> = setOf(
     "API_NOT_AVAILABLE",
     "UNRESOLVED_REFERENCE_WRONG_RECEIVER",
     "UNRESOLVED_IMPORT",
+    "DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE",
     "CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS",
     "NO_CONSTRUCTOR",
     "FUNCTION_CALL_EXPECTED",
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonTypeCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonTypeCheckers.kt
index 367b663b1e5..0433132570d 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonTypeCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonTypeCheckers.kt
@@ -17,6 +17,7 @@ object CommonTypeCheckers : TypeCheckers() {
         FirUnsupportedDefaultValueInFunctionTypeParameterChecker,
         FirUnsupportedModifiersInFunctionTypeParameterChecker,
         FirStarProjectionModifierChecker,
+        FirDuplicateParameterNameInFunctionTypeChecker,
         FirOptionalExpectationTypeChecker
     )
 }
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/type/FirDuplicateParameterNameInFunctionTypeChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/type/FirDuplicateParameterNameInFunctionTypeChecker.kt
new file mode 100644
index 00000000000..b2235d9f022
--- /dev/null
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/type/FirDuplicateParameterNameInFunctionTypeChecker.kt
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.analysis.checkers.type
+
+import org.jetbrains.kotlin.builtins.StandardNames
+import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.fir.declarations.getAnnotationByClassId
+import org.jetbrains.kotlin.fir.expressions.FirConstExpression
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.types.customAnnotations
+import org.jetbrains.kotlin.fir.types.type
+
+object FirDuplicateParameterNameInFunctionTypeChecker : FirTypeRefChecker() {
+    override fun check(typeRef: FirTypeRef, context: CheckerContext, reporter: DiagnosticReporter) {
+        if (typeRef !is FirResolvedTypeRef) return
+
+        val nameToArgumentProjection = typeRef.type.typeArguments.dropLast(1).groupBy {
+            val type = it.type ?: return@groupBy null
+            val annotation = type.customAnnotations.getAnnotationByClassId(StandardNames.FqNames.parameterNameClassId, context.session)
+            val nameEntry = annotation?.argumentMapping?.mapping?.get(StandardNames.NAME)
+            (nameEntry as? FirConstExpression<*>)?.value as? String
+        }
+
+        for ((name, projections) in nameToArgumentProjection) {
+            if (name != null && projections.size >= 2) {
+                reporter.reportOn(typeRef.source, FirErrors.DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE, context)
+            }
+        }
+    }
+}
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
index 9ea9d96c249..ba59fc31f37 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
@@ -192,6 +192,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DESERIALIZATION_E
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DIVISION_BY_ZERO
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DSL_SCOPE_VIOLATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DUPLICATE_LABEL_IN_WHEN
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_NOT_ALLOWED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_RECEIVER_NOT_ALLOWED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_SUPERTYPE
@@ -769,6 +770,7 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
         map.put(MISSING_CONSTRUCTOR_KEYWORD, "Use the 'constructor' keyword after the modifiers of the primary constructor.")
         map.put(UNRESOLVED_REFERENCE, "Unresolved reference ''{0}''.", NULLABLE_STRING)
         map.put(UNRESOLVED_IMPORT, "Unresolved reference ''{0}''.", NULLABLE_STRING) // &
+        map.put(DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE, "Duplicate parameter name in a function type.")
         map.put(UNRESOLVED_LABEL, "Unresolved label.")
         map.put(DESERIALIZATION_ERROR, "Deserialization error.")
         map.put(ERROR_FROM_JAVA_RESOLUTION, "Java resolution error.")
diff --git a/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt
index 5d6770c5b77..7966ee1d112 100644
--- a/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt
+++ b/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt
@@ -2,6 +2,6 @@ fun test0(f: (String, String) -> Unit) {
     f("", "")
 }
 
-fun test1(f: (a: Int, a: Int) -> Unit) {
+fun test1(f: <!DUPLICATE_PARAMETER_NAME_IN_FUNCTION_TYPE!>(a: Int, a: Int) -> Unit<!>) {
     f(1, 1)
 }
\ No newline at end of file