The thing that bothers me about this issue is the same experts who have declared the backward Bavarian crosses to be original are the same ones who will condemn a skull if it varies in the slightest way from the standard. These things were made when things were not standardized and were laid up by hand. there is going to be variation in different manufacturers and even in different runs.
There was another one of these backward crosses at SOS a few years ago, but I did not get a chance to look at it. When we can find two of them that are the same, then we can suspect that there is a possibility that they are stamped, but when the two examples that are known are definitely not the same, then we have to assume they are cast and one of a kind. They could have been made during the correct period on special order in mass produced crosses were not readily available or they could have been made after the fact for someone who wanted one for his own helmet. This would keep it out of the realm of fakes and this might be a likely possibility as they seem to be old and the reserve cross did not up grade a helmet enough to justify the expense of making the cross, unless there were collectors who wanted to complete their collection.