I don't think that either of them support broadcasting which you would probably need to multi-box unless you're planning on doing this through another method ???

There is also the synergy compile with broadcasting built into it as well thats linked in the WIKI and is available here -> http://www.dual-boxing.com/SynergyWBroad.zip

I'm also not sure but I "thought" that keyclone could go across multiple computers as well but I could be wrong (mac user here).