As I recall, the Devs actually said you could when someone asked during OB. In fact, they like it when you do that, it's more money for them.
Thanks, Rikaelus. I'll give that a try. If it doesn't work, I'll dump the problem on Cryptic's lap and let them transfer it over to the right account.
NO! Do not create a second account!
While logged into the STO website, just click the Redeem Your Key! box on the frontpage and activate it on your current account. You can stack all 20-whatever retail versions, if you bought them, into your one account. They have stated before in the FAQs, that the bonus items and 30 days per retail key will stack. Check out here: Pre-Order FAQ
Q: How much game time is included with the copy of the game?
A: Thirty days of game time is included with each retail copy of Star Trek Online. This stacks, so if you purchase three copies of the game, you will get 90 days of game time, as well as all the pre-order bonuses.
Q: Do the exclusive items stack? Can I get more than one thing?
A: Yes, different items stack. So if someone purchased multiple copies of the game from various retailers, he would receive all those items for EACH character created. Included playtime will still stack as well. However, the same bonus does not stack. So if someone purchases from Wal Mart twice, he cannot get two 500 point skill bonuses for the same character. (Each character will get one).
So if you apply both codes to one account, you'll receive two months of game time plus the respective bonuses provided from the retailers.
So, yeah, as others have said, you CAN apply multiple copies to the same account.