Been a while but there is a difference depending on your software level. It works different on older versions.
Your best option is to redesign so that you do not need this feature. It is poor design when traffic is sent to the wrong device to send traffic to external networks.
There is a option called same-security-traffic permit intra-interface. The really old version of asa do not support this concept at all if I remember correctly, the traffic is not allowed to go in and out the same interface.
Best option is to use layer 3 device other than the ASA as the gateway that does not have all the security restrictions a firewall does.