Please be more specific about what it is that you want to do.

You can open more than one pcf in PPENG and cut and paste or drag and drop between them.

You can also merge two pcfs using the Merge command in the File menu.

I'm not sure if you can have more than one Gallery open at a time, but you can add any quantity of additional graphics to the Gallery. BTW, not many folks use the Gallery feature. Most of us just use directories containing favorite button graphics.