I keep a G17 in mine for home defense with a couple spare mags laying in the bottom under the barrel. There is room for a second gun also laying in the bottom to the side and have had several customers tell me they keep their CCW in them at night as well. It does have to be upside down and reversed so th two guns will clear each other.
In the FAS1-Magnum, I think 3 would be possible to store in this manner since the holster is centered and the box is 1/2" wider and 1" longer. Perhaps one on each side.
I think there are a few other handgun safes that will store a couple handguns like the larger Ft. Knox and V-Line. Both these also use mechanical push button locks.