How to merge 2 albums same title and artist different contents

I struggle to understand the interaction between the tags I create using Music Tag Editor and those that are picked up by Roon - I have ended up with two tracks each with apparently (now) the same external tags appearing in two separate albums in Roon. How do I merge them into one album or get Roon to recognise that they have the same external Album tag and therefore should be together in one Album?

[Is there an idiot’s guide to all of tagging in Roon?]

Help really appreciated.

This might be helpful:

Also this on merging albums:

@Geoff_Coupe

Thank you. Really helpful.

I have externally tagged the names of the files, but when they come through to Roon, the tags don’t get used. How do I change that so that the tags from the external editor are used?