You can just use authorized.net without having merchant account privilege on eB...THAT will take ID, etc for each account. What you can do is convince customers to pay using their pp to authorized.net invoices...
Question:
Could u use one authroized.net account with mutiple ebays?
Answer:
NO. Each terminal has its own ap gateway.
Question: Can you open multiple merchant accounts?
Answer:
You can open about two, but it will be considered a high risk. You cant open 90 you will -be put on the black list by the banks. This is not paypal, you are dealing with direct banks.