Duplicate Volumes in Disk Utility

I've just noticed some duplicate volumes in Disk Utility - it seems that my entire hard drive is replicated. I ran First Aid on the main volume and got a message to say it couldn't be verified completely (see attached). I also have a new volume called Update.

I think this has come about because I created a new volume and installed a beta version of Big Sur on it, but then found I couldn't run my most used apps without installing them again, so deleted the volume.

Here is my question: is there a way to get rid of these items so that I can go back to a nice, tidy hard drive? What harm might be done by deleting the Update volume?