Blue post · Kaivax
No WoW Account Selector for Multiple Licenses—Second Login Disconnects First Player
KaivaxSummary
A player reported that two WoW accounts under one Blizzard account could not both log in: the second login disconnects the first and no account selector appears. Blizzard asked whether adding a separate test-region account would bring up a choice of account at login.
Read the original on Blizzard's forums
This is our own summary of what Blizzard posted, not Blizzard's text. The original is the authority.