Steps to Reproduce:
1. Turn on Content Log
2. Log into a realm   
3. or  Create a new world (survival/peaceful/show coords/start map and chest/no cheats) and place in realm slot and go in

Observed Results:
Content Log errors, see attached picture

Error Message in content log: [Log][warning]-The registry has already catalogued the tags. No tags should be added at this time.

Expected Results:
No content log errors, especially on a world with NO PACKS

Note: A lot of people are experiencing same thing and may think it is one of their packs as I did, which is why I created a world with nothing and went in.  Same thing so it is not the users.