Could you clarify what is meant by "DB89/99/18"??Easy question:
The frogs with strap and button are M57 frogs for the bayonet M57 issued with the Stgw 57.
M57 are more common than the original DB89/99/18 frogs. So then the greedy profiteers cut off the leather strap from the scabbard and supplement the bayonet with an M57 frog. The bayonet (or the scabbard) is then worthless from a collector's point of view.