--- main/format_cap.c	(Asterisk 13.5.0)
+++ main/format_cap.c	(working copy)
@@ -245,7 +245,10 @@
 			continue;
 		}
 
-		format = ast_format_create(codec);
+		format = ast_format_cache_get(codec->name);
+		if (!format || (codec != ast_format_get_codec(format))) {
+			format = ast_format_create(codec);
+		}
 		ao2_ref(codec, -1);
 
 		if (!format) {