Will my optional PowerCore plug-ins registered to one PowerCore also work another PowerCore?
PowerCore is a platform, which means the plug-ins will just as easily run on any PowerCore card / unit.
If you have different PowerCore devices connected to a single system, you will be able to run the optional plug-ins on all of the PowerCores in your system, provided the PowerCore to which you have registered your optional plug-in (-s), is present in the system, as it acts as the "copy protection dongle" for the plug-ins.
The same logic applies to running a PowerCore Unplugged alongside any other PowerCore in the same system.
All the included PowerCore plug-ins cannot run on the Unplugged by default, but if you have another PowerCore (ie. not an Unplugged) in the same system, that second PowerCore will -- just like with optional plug-ins -- act like a "copy protection dongle" and let you run the included PowerCore plug-ins on both PowerCores.