Hi Beth,
I don't think fake or reproduction is necessarily the case.
Quite often designs can appear either simultaneously, or with a short intervening period.
Recently I found a Riihimaki pattern that is very similar to Matura's "Praha" table-ware. I would not call either a fake, though there may exist an element of plagiarism, a not uncommon occurence with mass-produced glass.
Regards,
Marcus