Steps to replicate the issue (include links if applicable):

• Open PageCuration on a redirect with redirect categories
• Hit tag and add another redirect category

What happens?:
There are two rcat shells

What should have happened instead?:
All of the redirect categories should be under one rcat shell

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.): The diff where this happened was https://en.wikipedia.org/w/index.php?title=Day_of_Disaster&diff=prev&oldid=1175307507