It is possible to run 2 clients of the same coin (2xftc for example) on the same machine. You simply need to add the -datadir=c:\client1 on the first one and put the config file in there then change the rpcport/port in the feathercoin.conf file to a unique combination. Then on the second client client you specify -datadir=c:\client2 and so on. If you allow one of the clients to use the default location it won’t work.
I can only see why you would want to do the above on a pool though.