Sorry, I had to find this thread again...
Doc set it straight with his last post, also Crazyduck is right - the second incarnation of this model was called "Prodive."
Here's a
link to a NOAA safety warning concerning HP seat failures in the first stage (note name of regulators in the warning notice). This wasn't the problem I talked about in my first post, however. The original Royal (not the old double hose model, but the 2 stage model) had both large and small round holes on the coverplate of the second stage. The larger holes were in the center, the smaller on the outside. It free-flowed too much. The "slotted" style second stage cover replaced it.
The trade names this regulator went by include Royal SL, Royal Supreme, Pro Diver and ProDiver Supreme.
Hope this helps...