https://www.ebay.co.uk/itm/RARE-VIN...173334?hash=item5b5b52be96:g:3pkAAOSw9S9dTHejPurchases made through these links may earn this site a commission from the eBay Partner Network I suspect this may be a semi Franken. The movement seems to be a cal1205 but the case and dial are the later 1205-0 which used the cal65 movement. Case back numbers are 565100/01 and 2'556'937. The giveaway is the "65" in the first ref.
Hard to say whether that one's a franken or not - this one http://item.ocnk.net/product/6018 is quite a bit later but appears to have the 1205 movement (with swan neck regulator) and I've seen a few 865100 models with the 1205'. On the basis that there aren't likely to be many movements to go around (an uncommon watch with a case that has no melt value) and 1205 movements in non railrouter ref's usually lacked the hacking mechanism (ref's 412501-1 have these movements) I'd hazard a guess that there won't be many put togethers. Possibility remains that it's been recased with one of those sold on ebay but they all have crowns (with stems) and the watch you've linked has the wrong crown fitted which likely rules out a recent Franken. @Jonatan has a couple of these I think. He's bound to know more!
Is it possible that after UG produced the 1205-0 with the cal65 movement there were still cal1205 movements in stock which they used?
This is an enigma. The cases I have all came with the original crown and stem as mentioned by @rustynuts so if it was to be recased I would assume the correct crown would be used. @Moahunter I'm thinking that it's highly possible the factory just used the calibre they had on hand. There still a lot of information missing on these to know for sure.
That was the watch with the redone Chronometre dial. He recased it in the gold capped ebay case and then sold the dial separately as a refinished dial. I think he kept the steel Chronometre case. Should have probably just swapped the dial but so it goes.