I have the same double stitch on my wallet - in fact on all of the wallets I've ever had - and it's a result of the craftsperson 'sealing' the stitching so that it doesn't come undone. I personally would have a problem if there was some serious backtracking, but in this case it legitimately has a reason for being there just as some bags like the NF have that overlapping of the top trim.
I agree. I think all wallets are done this way to secure the stitch. Some places where the stich ends are just more obvious. It's just a part of the craftsmanship.