Can you have multiple instances of the same vip ?

Can you have multiple instances of the same vip ? No, you can't.

Could you use the same VIP for 2 different pools as long as the port etc is different? Sure you can. You can forward your traffic to any pool you need to, based on some criteria of your choice (port, source ip, host header, etc...). You would have to create an iRule though or use a HTTP policy, as the GUI just lets use specify one pool.