Only read the number of loops from the first frame

Tests/test_file_gif.py

@@ -772,9 +772,16 @@ def test_number_of_loops(tmp_path):
     im = Image.new("L", (100, 100), "#000")
     im.save(out, loop=number_of_loops)
     with Image.open(out) as reread:
-
         assert reread.info["loop"] == number_of_loops
 
+    # Check that even if a subsequent GIF frame has the number of loops specified,
+    # only the value from the first frame is used
+    with Image.open("Tests/images/duplicate_number_of_loops.gif") as im:
+        assert im.info["loop"] == 2
+
+        im.seek(1)
+        assert im.info["loop"] == 2
+
 
 def test_background(tmp_path):
     out = str(tmp_path / "temp.gif")

src/PIL/GifImagePlugin.py

@@ -244,15 +244,15 @@ def _seek(self, frame, update_image=True):
                         info["comment"] = comment
                     s = None
                     continue
-                elif s[0] == 255:
+                elif s[0] == 255 and frame == 0:
                     #
                     # application extension
                     #
                     info["extension"] = block, self.fp.tell()
                     if block[:11] == b"NETSCAPE2.0":
                         block = self.data()
                         if len(block) >= 3 and block[0] == 1:
-                            info["loop"] = i16(block, 1)
+                            self.info["loop"] = i16(block, 1)
                 while self.data():
                     pass
 
@@ -399,7 +399,7 @@ def _rgb(color):
 
         if info.get("comment"):
             self.info["comment"] = info["comment"]
-        for k in ["duration", "extension", "loop"]:
+        for k in ["duration", "extension"]:
             if k in info:
                 self.info[k] = info[k]
             elif k in self.info: