Meaning what though, the game will unlock and apply a new key to the current client? Or, that it will unlock and force the download of yet another copy of the same client. Twice. Yep, that's another 20GB.
Erm, when i right-clicked on my "Star Trek Online - Beta" and went to properties there was a link that took me directly to an activation page. I didnt need to re-download the client at all, just carried on using the beta one. It registered my Head-Start at the same time. Took like two seconds.
The problem is not with Steam its people not knowing how to use it properly.