Your LW on the 2nd computer will need a different port. Question is whether you are using your router in UPnP mode or port forwarded for the first computer. (Routers tend to reserve one port per application per computer, so a different application on same computer or any program on 2nd computer won't be able to use that same port.)

The port settings within LW are -> LW's menu bar, Tools > Options > Advanced > Firewall. And you can set the port to use there.

If problems arise connecting with it, check the port LW shows in that above window. If it's in UPnP mode then it will find its own port usually. If your router is properly UPnP capable (some router's UPnP is unreliable), then it should be ok on condition LW on 2nd computer doesn't try to use the same port as the first computer. Check that above window on both LW's. If they are trying to use the same port, then you might be safest to port forward the actual router to a different port from the first one.

Also keep in mind that whilst your 1st computer might be using a static ip, you may wish to set a static ip for the 2nd unless your ISP specifically provides a static ip service. (Networked computers will normally have a different ip address; eg: 192.0.0.1 & 192.0.0.2, etc.