TV characters have counterparts in other TV dimensions; we see this all the time. And there are plenty of characters from Toobworld that show up in the Tooniverse - Punky Brewster, Mork, Jeannie, the Fonz, the Brady Bunch, Laverne & Shirley, and Batman & Robin.
There's a Tooniverse character living in the Springfield area who has a doppleganger in the dimension that houses the new version of 'Human Target'. (As much as I like that show, it can't be in Earth Prime-Time because its Great Britain has a totally different Royal Family.)
The mobster Fat Tony was mentioned this past week on the show, but unlike with the original on 'The Simpsons', that Fat Tony is already dead; killed by the thugs working for Ilsa Pucci's lawyer.