PT version 5.1 supposedly had the ability to have multiple plug-in windows open at one time. I haven't upgraded my system yet, but I was working on another system that had 5.1.1 in it today and I couldn't get it to happen. What gives?
Each plugin (and other floating windows) has a "target" button that looks like a bull's eye. By defualt the target is active and is highlighted in red. When the "target" is highlighted or active, all plug-ins will pop up in that location. By clicking on the "target" and turning it grey to disable it, the next plugin you select will popup in a different location. This allows you to view more than one plugin at a time.