Was it multiple monitors or multiple systems? Can't see if there's another keyboard and mouse there in front of the one behind him. Though I suppose it was all supposed to be mainframe terminals (running Linux in the movie, which I'm not sure had a mainframe version, as I understand, it started as a Unix for desktops, where Unix was the mainframe OS).

Edit: the Linux thing was my own bad memory, Lex recognizes Unix, which is weird because it was an experimental unix filesystem browser UI and most kids wouldn't have access to machines that run any kind of unix, so it wouldn't have been a "I played with some computers in my garage" kind of thing. Though being Hammond's grandkids, it's not outside the realm of possibility that she did have access to a mainframe either through Hammond's companies or from access to universities and the like.