I used SQL Server configuration manager to enable TCP/IP on port 1433. I didn't have any problem but when I tried to enable another SQL service (different one) to listen on the same port I couldn't run it. When I stopped the first service there wasn't any problem. I also can run them together when only one of them has TCP enabled.
My question is why I can't run the both services together? I guess it has something to do with port but I thought that they just listen on this port so there shouldn't be problem.