diff --git a/test/built-ins/RegExp/prototype/exec/duplicate-named-groups-properties.js b/test/built-ins/RegExp/prototype/exec/duplicate-named-groups-properties.js
new file mode 100644
index 0000000000..4b960e2fbc
--- /dev/null
+++ b/test/built-ins/RegExp/prototype/exec/duplicate-named-groups-properties.js
@@ -0,0 +1,36 @@
+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Properties on groups object with duplicate named capture groups
+esid: prod-GroupSpecifier
+features: [regexp-duplicate-named-groups]
+includes: [compareArray.js]
+---*/
+
+const matcher = /(?:(?<x>a)|(?<y>a)(?<x>b))(?:(?<z>c)|(?<z>d))/;
+
+const threeMatchResult = matcher.exec("abc");
+assert.sameValue(threeMatchResult.groups.x, "b", "group x matches b");
+assert.sameValue(threeMatchResult.groups.y, "a", "group y matches a");
+assert.sameValue(threeMatchResult.groups.z, "c", "group z matches c");
+assert.compareArray(
+  Object.keys(threeMatchResult.groups),
+  ["x", "y", "z"],
+  "Properties of groups are ordered in RegExp source order despite y matching before x in this alternative"
+);
+
+const twoMatchResult = matcher.exec("ad");
+assert.sameValue(twoMatchResult.groups.x, "a", "group x matches a");
+assert.sameValue(twoMatchResult.groups.y, undefined, "group y does not match");
+assert.sameValue(twoMatchResult.groups.z, "d", "group z matches d");
+assert.compareArray(
+  Object.keys(twoMatchResult.groups),
+  ["x", "y", "z"],
+  "y is still present on groups object, in the right order, despite not matching"
+);
+
+const iteratedMatcher = /(?:(?:(?<x>a)|(?<x>b)|c)\k<x>){2}/;
+
+const matchedInPrevIterationResult = iteratedMatcher.exec("aac");
+assert.sameValue(matchedInPrevIterationResult.groups.x, undefined, "group x does not match in the last iteration");
diff --git a/test/built-ins/RegExp/prototype/exec/duplicate-named-indices-groups-properties.js b/test/built-ins/RegExp/prototype/exec/duplicate-named-indices-groups-properties.js
new file mode 100644
index 0000000000..08e5155a07
--- /dev/null
+++ b/test/built-ins/RegExp/prototype/exec/duplicate-named-indices-groups-properties.js
@@ -0,0 +1,36 @@
+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Properties on indices.groups object with duplicate named capture groups
+esid: prod-GroupSpecifier
+features: [regexp-duplicate-named-groups, regexp-match-indices]
+includes: [compareArray.js]
+---*/
+
+const matcher = /(?:(?<x>a)|(?<y>a)(?<x>b))(?:(?<z>c)|(?<z>d))/d;
+
+const threeMatchResult = matcher.exec("abc");
+assert.compareArray(threeMatchResult.indices.groups.x, [1, 2], "group x matches b");
+assert.compareArray(threeMatchResult.indices.groups.y, [0, 1], "group y matches a");
+assert.compareArray(threeMatchResult.indices.groups.z, [2, 3], "group z matches c");
+assert.compareArray(
+  Object.keys(threeMatchResult.indices.groups),
+  ["x", "y", "z"],
+  "Properties of groups are ordered in RegExp source order despite y matching before x in this alternative"
+);
+
+const twoMatchResult = matcher.exec("ad");
+assert.compareArray(twoMatchResult.indices.groups.x, [0, 1], "group x matches a");
+assert.sameValue(twoMatchResult.indices.groups.y, undefined, "group y does not match");
+assert.compareArray(twoMatchResult.indices.groups.z, [1, 2], "group z matches d");
+assert.compareArray(
+  Object.keys(twoMatchResult.indices.groups),
+  ["x", "y", "z"],
+  "y is still present on groups object, in the right order, despite not matching"
+);
+
+const iteratedMatcher = /(?:(?:(?<x>a)|(?<x>b)|c)\k<x>){2}/d;
+
+const matchedInPrevIterationResult = iteratedMatcher.exec("aac");
+assert.sameValue(matchedInPrevIterationResult.indices.groups.x, undefined, "group x does not match in the last iteration");
diff --git a/test/built-ins/String/prototype/match/duplicate-named-groups-properties.js b/test/built-ins/String/prototype/match/duplicate-named-groups-properties.js
new file mode 100644
index 0000000000..2a499ab3d8
--- /dev/null
+++ b/test/built-ins/String/prototype/match/duplicate-named-groups-properties.js
@@ -0,0 +1,36 @@
+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Properties on groups object with duplicate named capture groups
+esid: prod-GroupSpecifier
+features: [regexp-duplicate-named-groups]
+includes: [compareArray.js]
+---*/
+
+const matcher = /(?:(?<x>a)|(?<y>a)(?<x>b))(?:(?<z>c)|(?<z>d))/;
+
+const threeMatchResult = "abc".match(matcher);
+assert.sameValue(threeMatchResult.groups.x, "b", "group x matches b");
+assert.sameValue(threeMatchResult.groups.y, "a", "group y matches a");
+assert.sameValue(threeMatchResult.groups.z, "c", "group z matches c");
+assert.compareArray(
+  Object.keys(threeMatchResult.groups),
+  ["x", "y", "z"],
+  "Properties of groups are ordered in RegExp source order despite y matching before x in this alternative"
+);
+
+const twoMatchResult = "ad".match(matcher);
+assert.sameValue(twoMatchResult.groups.x, "a", "group x matches a");
+assert.sameValue(twoMatchResult.groups.y, undefined, "group y does not match");
+assert.sameValue(twoMatchResult.groups.z, "d", "group z matches d");
+assert.compareArray(
+  Object.keys(twoMatchResult.groups),
+  ["x", "y", "z"],
+  "y is still present on groups object, in the right order, despite not matching"
+);
+
+const iteratedMatcher = /(?:(?:(?<x>a)|(?<x>b)|c)\k<x>){2}/;
+
+const matchedInPrevIterationResult = "aac".match(iteratedMatcher);
+assert.sameValue(matchedInPrevIterationResult.groups.x, undefined, "group x does not match in the last iteration");
diff --git a/test/built-ins/String/prototype/match/duplicate-named-indices-groups-properties.js b/test/built-ins/String/prototype/match/duplicate-named-indices-groups-properties.js
new file mode 100644
index 0000000000..df5034ded1
--- /dev/null
+++ b/test/built-ins/String/prototype/match/duplicate-named-indices-groups-properties.js
@@ -0,0 +1,36 @@
+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Properties on indices.groups object with duplicate named capture groups
+esid: prod-GroupSpecifier
+features: [regexp-duplicate-named-groups, regexp-match-indices]
+includes: [compareArray.js]
+---*/
+
+const matcher = /(?:(?<x>a)|(?<y>a)(?<x>b))(?:(?<z>c)|(?<z>d))/d;
+
+const threeMatchResult = "abc".match(matcher);
+assert.compareArray(threeMatchResult.indices.groups.x, [1, 2], "group x matches b");
+assert.compareArray(threeMatchResult.indices.groups.y, [0, 1], "group y matches a");
+assert.compareArray(threeMatchResult.indices.groups.z, [2, 3], "group z matches c");
+assert.compareArray(
+  Object.keys(threeMatchResult.indices.groups),
+  ["x", "y", "z"],
+  "Properties of groups are ordered in RegExp source order despite y matching before x in this alternative"
+);
+
+const twoMatchResult = "ad".match(matcher);
+assert.compareArray(twoMatchResult.indices.groups.x, [0, 1], "group x matches a");
+assert.sameValue(twoMatchResult.indices.groups.y, undefined, "group y does not match");
+assert.compareArray(twoMatchResult.indices.groups.z, [1, 2], "group z matches d");
+assert.compareArray(
+  Object.keys(twoMatchResult.indices.groups),
+  ["x", "y", "z"],
+  "y is still present on groups object, in the right order, despite not matching"
+);
+
+const iteratedMatcher = /(?:(?:(?<x>a)|(?<x>b)|c)\k<x>){2}/d;
+
+const matchedInPrevIterationResult = "aac".match(iteratedMatcher);
+assert.sameValue(matchedInPrevIterationResult.indices.groups.x, undefined, "group x does not match in the last iteration");