do not parse the same single material twice

src/loaders/ObjectLoader.js

@@ -491,7 +491,7 @@ Object.assign( ObjectLoader.prototype, {
 				} else {
 
 					materials[ data.uuid ] = loader.parse( data );
-					cache[ data.uuid ] = loader.parse( data );
+					cache[ data.uuid ] = materials[ data.uuid ];
 
 				}