Meta Post: Actors Playing Alternate Universe Versions of Themselves

The problem I have with actors playing themselves in films is their relationship to other actors not playing themselves. For example, Cold Souls (haven't seen it) stars Paul Giamatti as Paul Giammati but what about Oscar-nominated David Strathaim? In this alternate universe, is there a David Strathaim? Does this character David Strathaim is playing look just like this this universe's David Strathaim?

Isn't kind of a kick in the face to these accessory actors? It basically implies that we can suspend our disbelief that David Strathaim is not David Strathaim even if Paul Giamatti is playing Paul Giamatti. It creates an actor hierarchy where we cannot believe a less famous actor is playing themselves if there is also a more famous actor playing a fictional character.

And don't get me started with Julia Roberts playing a fictional character that apparently looks just like Julia Roberts in Ocean's 12. Does Confessions of a Dangerous Mind not exist in the Ocean's universe? If it does, George Clooney must exist. Then is not George Clooney's character in the Oceans movies the splitting image of George Clooney in Confessions of a Dangerous Mind!? I have a real problem with this!