I run a MC 18w50a Server on a Windows Server 2016 Machine with the latest JRE, previously Server JRE 8u191. We have a large selfmade Village with about 30 villagers. After some time, they "duplicate". Weve got about 50-60 now, and we used some name Tags prior duplication. Now instead of 3 Farmers we have 6+, which are Sharing the same 3 names all over and they Offer the same trades. And several "Dinnerbones" Walking upside down (we had one, now multiple). The Server is only accesed locally (3 Players) and noone summoned more. I've checked the logs, they're as they should. I'll Post Pictures and more Infos later this day
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EDIT: it seems like it has to do with Dimension loading. After Entering and exiting the Nether, i've got reported that the villagers duplicated again. The Server crashed afterwards, got to check the logs later