Silas,
I just posted on your other thread and will not bother everybody with a repeat. I will say that there were many marine youth organizations in Germany and Austria before 1933 and all these boys had the Donald Duck style flat hat for the most part. Of course after the rule banished those organizations and merged them into the MHJ the old caps were used for a period of time. Maybe a long period of time. I have had sewn tallies, meaning the young man's mother probably stitched it out on her sewing machine (this was an Austrian town in this case) probably waiting for the official tally to arrive. I am sure the same thing happened early on with the caps in that the tallies started to arrive, maybe in some cases before the RZM tagged caps, and the boys just used the old caps for the time being. Or maybe that particular MHJ unit was not so strict as compared to other units and nobody cared what cap was used, official or not.
However, all that said, you cannot know for sure, generally speaking but not in a all cases, where the unofficial cap came from. Therefore, if the collector of MHJ caps is comfortable, go ahead, buy it, but the price has to reflect the problem. It comes down to money and valuation.