[runtime] Fix a problem with PR mono/mono#19361. (#34299)

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Co-authored-by: vargaz <vargaz@users.noreply.github.com>

Author: monojenkins

src/mono/mono/metadata/metadata.c

@@ -3379,17 +3379,20 @@ MonoImageSet *
 mono_metadata_merge_image_sets (MonoImageSet *set1, MonoImageSet *set2)
 {
 	MonoImage **images = g_newa (MonoImage*, set1->nimages + set2->nimages);
+
+	/* Add images from set1 */
 	memcpy (images, set1->images, sizeof (MonoImage*) * set1->nimages);
 
 	int nimages = set1->nimages;
 	// FIXME: Quaratic
-	for (int i = 0; i < set1->nimages; ++i) {
+	/* Add images from set2 */
+	for (int i = 0; i < set2->nimages; ++i) {
 		int j;
-		for (j = 0; j < set2->nimages; ++j) {
-			if (set1->images [i] == set2->images [j])
+		for (j = 0; j < set1->nimages; ++j) {
+			if (set2->images [i] == set1->images [j])
 				break;
 		}
-		if (j == set2->nimages)
+		if (j == set1->nimages)
 			images [nimages ++] = set2->images [i];
 	}
 	return get_image_set (images, nimages);