diff --git a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.errors.txt b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.errors.txt
index 62872f6c806..d210588234d 100644
--- a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.errors.txt
+++ b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.errors.txt
@@ -17,9 +17,11 @@ tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts(7,34): error TS2300: Duplicate identifier 'e'.
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts(7,39): error TS2300: Duplicate identifier 'e'.
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts(7,48): error TS2300: Duplicate identifier 'e'.
+tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts(8,14): error TS2300: Duplicate identifier 'f'.
+tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts(8,20): error TS2300: Duplicate identifier 'f'.
 
 
-==== tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts (19 errors) ====
+==== tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts (21 errors) ====
     
     function f0(a, [a, [b]], {b}) { }
                 ~
@@ -65,6 +67,9 @@ tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts
 !!! error TS2300: Duplicate identifier 'e'.
                                                    ~
 !!! error TS2300: Duplicate identifier 'e'.
-    
-    
-    
\ No newline at end of file
+    function f6([f, ...f]) { }
+                 ~
+!!! error TS2300: Duplicate identifier 'f'.
+                       ~
+!!! error TS2300: Duplicate identifier 'f'.
+    function f7(a, func = (a) => { return 1 }) { }  // not error
\ No newline at end of file
diff --git a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.js b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.js
index cdf70b29835..0c1eb5f3210 100644
--- a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.js
+++ b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration1.js
@@ -6,9 +6,8 @@ function f2({b}, {b}) { }
 function f3([c,[c],[[c]]]) { }
 function f4({d, d:{d}}) { }
 function f5({e, e: {e}}, {e}, [d,e, [[e]]], ...e) { }
-
-
-
+function f6([f, ...f]) { }
+function f7(a, func = (a) => { return 1 }) { }  // not error
 
 //// [duplicateIdentifierBindingElementInParameterDeclaration1.js]
 function f0(a, _a, _b) {
@@ -37,3 +36,9 @@ function f5(_a, _b, _c) {
         e[_i - 3] = arguments[_i];
     }
 }
+function f6(_a) {
+    var f = _a[0], f = _a.slice(1);
+}
+function f7(a, func) {
+    if (func === void 0) { func = function (a) { return 1; }; }
+} // not error
diff --git a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.errors.txt b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.errors.txt
index 8a6df4b075b..e3d1dc621f8 100644
--- a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.errors.txt
+++ b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.errors.txt
@@ -17,9 +17,11 @@ tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts(8,35): error TS2300: Duplicate identifier 'e'.
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts(8,40): error TS2300: Duplicate identifier 'e'.
 tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts(8,49): error TS2300: Duplicate identifier 'e'.
+tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts(9,14): error TS2300: Duplicate identifier 'f'.
+tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts(9,20): error TS2300: Duplicate identifier 'f'.
 
 
-==== tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts (19 errors) ====
+==== tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts (21 errors) ====
     
     "use strict"
     function f0(a, [a, [b]], {b}) { }
@@ -66,6 +68,9 @@ tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts
 !!! error TS2300: Duplicate identifier 'e'.
                                                     ~
 !!! error TS2300: Duplicate identifier 'e'.
-    
-    
-    
\ No newline at end of file
+    function f6([f, ...f]) { }
+                 ~
+!!! error TS2300: Duplicate identifier 'f'.
+                       ~
+!!! error TS2300: Duplicate identifier 'f'.
+    function f7(a, func = (a) => { return 1 }){ }  // not error
\ No newline at end of file
diff --git a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.js b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.js
index 46f59c6c96d..e423b035d9d 100644
--- a/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.js
+++ b/tests/baselines/reference/duplicateIdentifierBindingElementInParameterDeclaration2.js
@@ -7,9 +7,8 @@ function f2({b}, {b}) { }
 function f3([c, [c], [[c]]]) { }
 function f4({d, d: {d}}) { }
 function f5({e, e: {e}}, {e}, [d, e, [[e]]], ...e) { }
-
-
-
+function f6([f, ...f]) { }
+function f7(a, func = (a) => { return 1 }){ }  // not error
 
 //// [duplicateIdentifierBindingElementInParameterDeclaration2.js]
 "use strict";
@@ -39,3 +38,9 @@ function f5(_a, _b, _c) {
         e[_i - 3] = arguments[_i];
     }
 }
+function f6(_a) {
+    var f = _a[0], f = _a.slice(1);
+}
+function f7(a, func) {
+    if (func === void 0) { func = function (a) { return 1; }; }
+} // not error
diff --git a/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts b/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts
index e5c5965301e..9d4a2331b45 100644
--- a/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts
+++ b/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration1.ts
@@ -6,5 +6,5 @@ function f2({b}, {b}) { }
 function f3([c,[c],[[c]]]) { }
 function f4({d, d:{d}}) { }
 function f5({e, e: {e}}, {e}, [d,e, [[e]]], ...e) { }
-
-
+function f6([f, ...f]) { }
+function f7(a, func = (a) => { return 1 }) { }  // not error
\ No newline at end of file
diff --git a/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts b/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts
index 0ed6100ca34..f42e490dae1 100644
--- a/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts
+++ b/tests/cases/compiler/duplicateIdentifierBindingElementInParameterDeclaration2.ts
@@ -7,5 +7,5 @@ function f2({b}, {b}) { }
 function f3([c, [c], [[c]]]) { }
 function f4({d, d: {d}}) { }
 function f5({e, e: {e}}, {e}, [d, e, [[e]]], ...e) { }
-
-
+function f6([f, ...f]) { }
+function f7(a, func = (a) => { return 1 }){ }  // not error
\ No newline at end of file