It sounds like you may have associated your Auction Sniper account inadvertently with your second eBay account when you generated the link to eBay. This is the only way our service would bid on any account - Auction Sniper can only place bids on the eBay account it is linked to.
You can check which eBay account you have associated to your Auction Sniper account at any time after logging in. Just select Modify Account from the My Snipes menu and then check on the eBay Connection tab and it will show the username of the related eBay account.
If you wish to associate your Auction Sniper account with a different eBay account, just generate a new link to the other eBay account and then the service will bid for you on that account.