minecraft server 15w32b

this should not come up in the log and the code should not be executed in the first place

When i logged into a snapshot server in the log when i was loading new chunks it comes up with this
[(time) WARN]: Tried to add entity (entity name) with duplicate UUID 906ea7d8-f55f-4c1b-bc00-847abededcb3

Steps to Reproduce:
1. load up the server
2. log on to the server
3. load new chunks and check the log