[gemwin x] will render at x fps, in this case 1 fps or 2 fps. If not argument is supplied Gem will render at 20 fps.
You can not create 2 Gem windows in the same PD instance, although it will be in in differents patches. You can do it with two PD instances and intercommunicates it with netsend/netreceive.
In the same PD instances you must first destroy the window in a patch, set the new values for the new window and create it again. Perhaps a delay to the bang wich creates the new window would be fine. Note that this is not 2 Gem windows, only destroys and creates one Gem window.
If you don't send new values before creating the new window will be equal to the old window.
Also you can use two gemheads chains in the same patch and both will render in the same Gem window.
Attach a example patch to show us better what are you trying..