fix for duplicates skipping

Author: IldarKhayrutdinov

src/ImageSharp/Metadata/Profiles/Exif/ExifReader.cs

@@ -490,8 +490,9 @@ private void Add(IList<IExifValue> values, ExifValue exif, object? value)
 
         foreach (IExifValue val in values)
         {
-            // Sometimes duplicates appear, can compare val.Tag == exif.Tag
-            if (val == exif)
+            // to skip duplicates must be used Equals method,
+            // == operator not defined for ExifValue and IExifValue
+            if (exif.Equals(val))
             {
                 Debug.WriteLine($"Duplicate Exif tag: tag={exif.Tag}, dataType={exif.DataType}");
                 return;

tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs

@@ -10,7 +10,6 @@
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Tests.TestUtilities;
-using static SixLabors.ImageSharp.Metadata.Profiles.Exif.EncodedString;
 
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Jpg;
@@ -496,17 +495,15 @@ public void Issue2857_SubSubIfds<TPixel>(TestImageProvider<TPixel> provider)
         Assert.Equal("Carers; seniors; caregiver; senior care; retirement home; hands; old; elderly; elderly caregiver; elder care; elderly care; geriatric care; nursing home; age; old age care; outpatient; needy; health care; home nurse; home care; sick; retirement; medical; mobile; the elderly; nursing department; nursing treatment; nursing; care services; nursing services; nursing care; nursing allowance; nursing homes; home nursing; care category; nursing class; care; nursing shortage; nursing patient care staff\0", exifProfile.GetValue(ExifTag.XPKeywords).Value);
 
         Assert.Equal(
-            new EncodedString(CharacterCode.ASCII, "StockSubmitter|Miscellaneous||Miscellaneous$|00|0000330000000110000000000000000|22$@NA_1005010.460@[email protected]$$@$@26$$@$@$@$@205$@$@$@$@$@$@$@$@$@43$@$@$@[email protected]$$@90$$@22$@$@$@$@$@$@$|||"),
+            new EncodedString(EncodedString.CharacterCode.ASCII, "StockSubmitter|Miscellaneous||Miscellaneous$|00|0000330000000110000000000000000|22$@NA_1005010.460@[email protected]$$@$@26$$@$@$@$@205$@$@$@$@$@$@$@$@$@43$@$@$@[email protected]$$@90$$@22$@$@$@$@$@$@$|||"),
             exifProfile.GetValue(ExifTag.UserComment).Value);
 
+        // the profile contains 4 duplicated UserComment
+        Assert.Equal(1, exifProfile.Values.Count(t => t.Tag == ExifTag.UserComment));
+
         image.Mutate(x => x.Crop(new(0, 0, 100, 100)));
 
         image.Save(ms, new JpegEncoder());
-
-        foreach (IExifValue val in image.Metadata.ExifProfile.Values)
-        {
-            this.Output.WriteLine($"{val.Tag}={val.GetValue()}");
-        }
     }
 
     private static void VerifyEncodedStrings(ExifProfile exif)