Master replicas scanned Prepro v3 helmet, not actually the ESB helmet, and when they scanned it, I guess the visor was not set in properly or whatever, but that's the image that was recorded on computer, so that's what MR thought it should look like.
The fact that now another entity has put the pinch in theirs is perfect to illustrate my long standing point that you should never attempt to replicate a replica, because then you perpetuate any mistakes as well as adding more of your own.
I've seen a lot of people use pictorial reference of replicas as the basis for their own replicas, rather than try to look at the pictorial reference of the actual item. Eventually people take things for granted as being correct.