That's what I did, I duplicated the library and renamed it, also renamed all references of it in the code. Didn't rename all the defines, tried it only with one key to check if it works before I'd go on renaming all of them but it didn't. When you say instance, how do you mean that? Wouldn't I just do this if, say, I renamed the library to PS2keyboard2:
</PS2Keyboard2 keyboard2;/>
It's 2 numeric keypads, not keyboards. I've built a MIDI control surface and they are part of it.