Each SlingStudio unit acts as its own access point, so you should not have two units on the same Wi-Fi network. Along with the potential for confusion, the SlingStudio hub's intensive network bandwidth requirements could make for an unacceptable product experience with more than one unit on the same Wi-Fi network.
However, you can have more than one SlingStudio unit in the same room or area. Just make sure that they're not accessing the same Wi-Fi network.