The boots seem like out from different universe and kinda ruins the character, i suggest going with something more cute/toyish, not with boots like that
I also would question why your trying to do this? Typically this is the type of thing game hacks do, which I am willing to guess is exactly what your trying to do.
Copying screen buffer is not a hack, it does not change or automate any of the behaviour of the software, if doing that would be considered hack, then using things like fraps or any other screen recording software would be bannable offense.
I know about that spazzarma api hook, but its overly bloated with extra threads, and probably even changes running application by running CLR runtime host on it, and i dont want that. Also requires your assembly to be installed in GAC.
Why would i use complete library only to install a hook to 2 functions? Its also not free for commercial and limited in express edition, lets not be ridicilous here.
I doubt there would be other way of doing that besides having to transfer texture memory from one gpu to cpu memory and then creating a texture on second gpu from that memory.
Also, calling one of your gpus a 'slave' is not a nice thing to do, it makes gpu sad.