Multiple non-existent monitors detected - E6540, Windows 10

I have a latitude E6540, windows 10 64 bit, with the following display adaptors and drivers:

• AMD Radeon 8790M, driver version 21.19.407.0 dated 12/19/2016
• Intel HD Graphics 4600, driver version 20.19.15.4531 dated 9/29/2016

When running stand alone, it sees a single display. As soon as I hook up either another display to the VGA port or connect it to a pro 2 docking port with another display (the same VGA display as used directly on the laptop connection), the system detects SIX monitors, not just one.

Has anyone seen this phenomena before?  If so, what is the cure?

I ran into the problem when I placed the laptop into the docking port and all displays went black. I had to use the Windows-P down down enter to get my display back, even after it was disconnected from the docking port.

I've already uninstalled the drivers and reinstalled them with no changes.