I haven't seen a thread like that around here, so why not go ahead and get the conversation started...
The only one that comes to mind for me is Brent Corrigan, who, for years, played up his similarity to Zac Efron (during the HSM years.)
There are plenty of porn stars that adopt names similar to celebrities, but they rarely look anything like their namesakes. There are probably a dozen performers using the name "Tatum" but they're a poor substitute for the real Channing guy.