I am confused by that second buckle too.
Those two in the wiki image are from my collection
. They consist of a buckle attached to a rectangular openwork plate which is attached to a smaller thin plate by some rivets. The openwork plate was on top of the belt leather, and I believe that the small thin plate was under the belt leather. Thus the belt leather was sandwiched between the plates. The belt leather ended at the buckle but extended out the "open" end between the plates.
Unless I am missing something, on your example the second buckle would seem to prevent the leather extending out. So it would not seem to be possible to use it on a belt.
So I can only see two possibilities. Fake
made by someone who does not understand them - though the rest of the design is very good
. Or, the second buckle was added latter as some sort of modification - it is much cruder. It could have made the entire thing into a sort of buckle. So instead of going on the end of the belt leather it would have been attached to it.
PS I agree with you dating by style