MSM does not impose any restriction except that I could only fit one MPG in the jogging panel on the screens. This was a trade off between generality and complexity - we figured one MPG covered most MPG users.
So if you have two, then you need to select the specific axis, which is reduced functionality, thus, both are not operatable at the same time....?
On a lathe it is realy nice to have two mounted on the carriage such that you duplicate a natural manual operation. I know this is for
the mill but just thought i would throw it out. When used on the mill, using say CopyCat to scan / get Gcode for a piece then two are used to advantage since you don't need to distract thinking while working.
RICH