You can NOT have two services listening on the same protocol/port at the same time, period.

There is a small loophole to that - the actual restriction is:
You can NOT have two services listening on the same protocol/port at the same time at the same IP address.

So - one possible workaround would be to listen ad different IP addresses, forwarding from one to the other.

There is a discussion of somewhat less clunky solutions, mirroring traffic from one port to another at:
http://stackoverflow.com/questions/7247668/duplicate-tcp-traffic-with-a-proxy.