Absolutely - assuming your computer has enough RAM and CPU power to run multiple programs at the same time, and your host program can converse via ReWire with multiple programs simultaneously.

We routinely, for example, ReWire both Propellerhead Reason and Submersible Music DrumCore to Digidesign Pro Tools LE at the same time. In Pro Tools, it's simply a matter of instantiating the ReWire plug-in for each application that you want to slave on a separate track.