diff --git a/test/formats/test_asf.py b/test/formats/test_asf.py
index 0fe185092..333016dd5 100644
--- a/test/formats/test_asf.py
+++ b/test/formats/test_asf.py
@@ -8,7 +8,14 @@ from picard.formats import (
     ext_to_format,
 )
 
-from .common import CommonTests
+from .common import (
+    CommonTests,
+    load_metadata,
+    load_raw,
+    save_metadata,
+    save_raw,
+    skipUnlessTestfile,
+)
 from .coverart import CommonCoverArtTests
 
 
@@ -29,6 +36,19 @@ class CommonAsfTests:
             for tag in self.replaygain_tags.keys():
                 self.assertTrue(fmt.supports_tag(tag))
 
+        @skipUnlessTestfile
+        def test_replaygain_tags_not_duplicated(self):
+            # Ensure values are not duplicated on repeated save
+            tags = {
+                'Replaygain_Album_Peak': '-6.48 dB'
+            }
+            save_raw(self.filename, tags)
+            loaded_metadata = load_metadata(self.filename)
+            save_metadata(self.filename, loaded_metadata)
+            raw_metadata = load_raw(self.filename)
+            self.assertFalse('Replaygain_Album_Peak' in raw_metadata)
+            self.assertTrue('REPLAYGAIN_ALBUM_PEAK' in raw_metadata)
+
 
 class ASFTest(CommonAsfTests.AsfTestCase):
     testfile = 'test.asf'
diff --git a/test/formats/test_id3.py b/test/formats/test_id3.py
index f39c4acfc..4d904942c 100644
--- a/test/formats/test_id3.py
+++ b/test/formats/test_id3.py
@@ -211,6 +211,18 @@ class CommonId3Tests:
             for (key, value) in self.replaygain_tags.items():
                 self.assertEqual(loaded_metadata[key], value, '%s: %r != %r' % (key, loaded_metadata[key], value))
 
+        @skipUnlessTestfile
+        def test_replaygain_tags_not_duplicated(self):
+            # Ensure values are not duplicated on repeated save
+            tags = mutagen.id3.ID3Tags()
+            tags.add(mutagen.id3.TXXX(desc='Replaygain_Album_Peak', text='0.978475'))
+            save_raw(self.filename, tags)
+            loaded_metadata = load_metadata(self.filename)
+            save_metadata(self.filename, loaded_metadata)
+            raw_metadata = load_raw(self.filename)
+            self.assertFalse('TXXX:Replaygain_Album_Peak' in raw_metadata)
+            self.assertTrue('TXXX:REPLAYGAIN_ALBUM_PEAK' in raw_metadata)
+
 
 class MP3Test(CommonId3Tests.Id3TestCase):
     testfile = 'test.mp3'
diff --git a/test/formats/test_mp4.py b/test/formats/test_mp4.py
index e21e4a439..9c3df04c6 100644
--- a/test/formats/test_mp4.py
+++ b/test/formats/test_mp4.py
@@ -5,6 +5,8 @@ from picard.formats import ext_to_format
 from .common import (
     CommonTests,
     load_metadata,
+    load_raw,
+    save_metadata,
     save_raw,
     skipUnlessTestfile,
 )
@@ -53,6 +55,18 @@ class MP4Test(CommonTests.TagFormatsTestCase):
         for (key, value) in self.replaygain_tags.items():
             self.assertEqual(loaded_metadata[key], value, '%s: %r != %r' % (key, loaded_metadata[key], value))
 
+    @skipUnlessTestfile
+    def test_replaygain_tags_not_duplicated(self):
+        # Ensure values are not duplicated on repeated save
+        tags = mutagen.mp4.MP4Tags()
+        tags['----:com.apple.iTunes:Replaygain_Album_Peak'] = [b'-6.48 dB']
+        save_raw(self.filename, tags)
+        loaded_metadata = load_metadata(self.filename)
+        save_metadata(self.filename, loaded_metadata)
+        raw_metadata = load_raw(self.filename)
+        self.assertFalse('----:com.apple.iTunes:Replaygain_Album_Peak' in raw_metadata)
+        self.assertTrue('----:com.apple.iTunes:REPLAYGAIN_ALBUM_PEAK' in raw_metadata)
+
 
 class Mp4CoverArtTest(CommonCoverArtTests.CoverArtTestCase):
     testfile = 'test.m4a'