I don't know if it works all the time. Take a look at my Party bonus account screen:
http://www.colby.edu/fencing/party.jpg
Last month, I got the pop up about 15to100more as you can see. I clearned that bonus. This month, the same offer came up, but instead of using it I put in the 20to100more bonus (which was never offered to me). Cleared that fine. I then withdrew $500 from my account, and redeposited using both the 30to100more and the 15to100more. This did not appear in the bonus account. You can see that it says Elapsed in the status (I have heard the withdrawing of money cancled the bonus, it was also done on the 16th).
What interests me is the lower field, which I've never payed much attention to: Bonus promotion details. Now the first bonus in december, the one where I used the 20to100bonus that was never offered to me--did not appear in that box. Now my girlfriend's offer "15to100gift" appears in that bonus promotion details box. The theory I am working on is that any bonus that is not in the "bonus promotion details" box ANYONE can use, no matter what pop-up you get. However, if the offer you recieve is listed in the "bonus promotion details" then it is account specific. Can anyone help me verify this?