Aweber modification required

Hi, When someone signs up for my free newsletter on my site, they are added to my aweber account list. However, I would like a modification, which means that they will be added to 2 separate accounts at the same time. (I have 2 separate aweber accounts). Please note, on Aweber I have single optin on both my accounts, therefore I still only want single optin for both accounts when you do the modification. Please do not bid if your implementation requires double optin. Thanks!