My car had a replacement rear door fitted recently but it seems to be less substantial than the original - when I knock on it, it sounds different from the other doors. I can’t see any stamping on any of the doors but I’d have thought that they’d have some marking that’d identify them as VAG doors. Is there a way of telling? 
 

The other possibility is that the door is missing a sound deadening pad or similar but without taking off the door card, I can’t be sure.

Almost certainly the sound deadening mat has not been replaced. Was it replaced via a claim? If so, the insurer probably didn’t authorise the mat. If you paid for the repair, go and ask the bodyshop to fit it. 

35 minutes ago, numskull said:

Almost certainly the sound deadening mat has not been replaced. Was it replaced via a claim? If so, the insurer probably didn’t authorise the mat. If you paid for the repair, go and ask the bodyshop to fit it. 

Thanks - I’ll get back on to the body shop 

I very much doubt that anybody would tool up to provide pattern part door assemblies, door skins perhaps but even then I am probably talking rubbish based on experience from a previous century.

 

Door assemblies might be available on a parallel market but they will have come from the same press tooling and if the vehicle is still in production from the same factory.

 

It does sound like (pun unintended) that the sound deadening pad has been omitted, good on you for noticing!

Chances are the sound deadening hasnt been replaced like for like.