Check my previous post again. I had edited it.
There's a way to confirm if the low-res is also embedded or not.
Edit:
Maybe I've misunderstood you.
The other was a local file.
Are you saying that you are now positive that the other album cover that MB is picking up is a local image located in your music file's folder?
I already spend hours on end on social media. Might as well spare a few of those to a greater purpose here.