Nope that's not how it works, it won't even run twice because of the Machine ID protection, but if you would get it to run it would only do the same work double instead of at double speed. And probably corrupting the WU in the process.
so what you can do is copy the files from your client folder (not the work folder) and run a second client under a differen Machine ID. (one client per real core, so not one per thread). But if you're going for points and folding 24/7 a SMP client will yield much higher PPD.