If you played Old Republic, you may be thinking of that game. That did happen over there.
Here in Retail, as Vrak said, we have Connected Realms, which are smart mergers. They link together servers so that they’re the same community, but they keep their server identification, so there is no loss of names. If there was a Sendryn on Kirin Tor and my character on Sentinels, we’d be distinguished by the server name.