if you are talking abt 2 interfaces on A single ASA then that cant be done ..
but 2 ASA's can have same IP address conencted to 2 Core switches.. i was still getting the grasp of Failover scenarios with active active failove ul have to set up multiple contexts in the asa .. then you can give 2 different contexts a same ip address..
try to find Active/Active failover example on cisco... Document ID: 91336
plz rate if it helps.. :-)