Yes I would say Deschler did make unmarked kvk's in the early years
"In all my years as a soldier, I have never seen men fight so hard." - SS Obergruppenfuhrer Wilhelm Bittrich - Arnhem
I see no reason to to think Deschler didn't make unmarked KVKs. They are certainly known for making a wide range of awards and these have turned up unmarked but have been attributed to Deschler due to the characteristics from this maker. With KVKs, it may be a little more hard to determine.
Looking for LDO marked EK2s and items relating to U-406.....
thank you for opinions