Depth is an important factor. Need to be able to scoot back and get down on the rifle without hitting the back of the blind.
Every time I’ve had 2 in a blind or seen others doing so, it’s one person taking a second one (guest, girlfriend/wife, kid, grandkid) hunting, so really needs to be optimized toward a single shooter.
More width means more shooting arc. I’d recommend windows/ports on all 4 sides with the ability to hang a curtain (no backlighting) on the back (door) side. Shooting out a side port sucks on a lot of blinds, but it is better than having no option and watching a deer walk because it’s at an awkward angle. You set up facing your most likely angle of approach, but critters don’t always cooperate.
If you have opening ports/windows, make sure they open and close quietly.
A low shelf for binos, water bottles etc is never a bad idea.
A blind for 2 needs a way to rack rifles where you don’t knock them over or make noise moving them to get a shot, especially if there’s really one shooter but two rifles. I can’t tell you how many times the “guide” looks through binos or is looking around while the shooter is setting up a shot and his knee or something hits a rifle propped up against a wall/corner and makes noise, but it happens a lot.