There is only a single bead lock wheel. A true beadlock will have a standard bead on the backside, and a bolt on Flange (bead) on the outside. There is a ridge on the back side of the tire bead and the flange of the bolt on piece clamps the bead on both sides. Prevents the tire from spinning on the wheel at low pressure. Most of what I've seen are around 450 a wheel...
Here is a Dirt Everyday video showing a true beadlock on a Raptor.
Your post is a bit confusing. There are several styles of bead locks. Single, double, both with rings, doubles with liners like Humvee rims, internal bead locks that don't require any bolting, and mechanical internal systems with clamps.
Technically, beadlocks are not DOT approved...so....
Technically, the DOT doesn't approve anything. If you are a supplier to the automotive industry, you build your parts to be compliant with the specifications that the DOT has come up with for each item that affects safety, etc.
No one has yet found a specific law on the books in any State that specifically makes bead locks illegal unless it was in the last couple of years.
Not to mention it is one of the higher pinnacles of hypocrisy to even question DOT compliance of bead lock rims by most rig owners.
The first thing that most do when they get their rig home is start taking it as far away from compliance as possible.
Ride height that affects crash test standards, yeah, screw that, I'm lifting it.
Bumpers that crumple as part of the crash test to slow down damage to occupants, screw it, I'm hanging giant chunks of steel in place of the stock ones. There are many other things but that should give an idea as to why I find it very odd that compliance is questioned for a single item and nothing else. When is the last time anyone looked at a tire they just bought to see if the DOT stamp was on it?