Copy? Probably not easily. You could go in by hand in the Dependency Graph, grab each node, dupe it, and re-connect it to your new hand. What a pain that would be. You could write a script to batch it, that might be a better option. Also, a quicker method would be to dupe your hand with "upstream graph" checked on, and then negative scale it, but I never recomend negative scaling joints. It WILL dupe the connections to the set driven keys, and dupe the keys etc, but this method tends to make your scene "messy", with arbitrarily named nodes, and, of course, funny scaled joints. So to answer your question, yes you can do it, no, it's not easy 