I think this might make four known.
The one on display at EMP is painted white. Then there's the walnut one in the video which apparently belongs to EMP senior curator Peter Blecha. The third one is the walnut example that Moonshine measured and played (see the other Audiovox thread). IIRC that one came from Gruhn in Nashville.
In the auction, Greg says "(One of the model 736 basses is in the Paul Allen EMP museum in Seattle and the other one is held by a private collector of vintage guitars.)" and "This electric bass guitar has been owned for over 60 years by one owner and was purchased directly from my grandfather, Paul Tutmarc." So it must be different from the one in the video and the one Moonshine played, and it's obviously not the painted one on display at EMP.
BTW, that "recent" Vintage Guitar story was from 1999.