Imported photos now end up in a virtual copy of my D: drive

As of a few weeks ago, when I import photos into Lightroom Classic 9.2.1 (CR 12.2.1) the photos now end up in a virtual copy of my D drive.

The imported files are physically copied to the correct drive and folder, but Lightroom seems to see it as a different drive to where my existing photos are stored.

And so when I click on the library folder for my existing photos, the newly added ones are not present, and when I click on the second copy of the D drive (in the library list) the newly added photos are there.

I can "move" the photos (physically they are not moved) but this is a nuisance. 

What is going on?

See attached image of my library folders

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