What file extension do these files have? .lrcat or .lrcat.zip?
With either, depending on what version of LR you are using, they could be Backups of your main catalog file. By Default LR is set to create a backup of the catalog file once a week. If you don't clear out the older ones they can add up, depending on the original size of your catalog file.
With LR 5 and previous versions the backups were just copies of your catalog. With LR 6/CC Adobe started creating Zip compressed files for the backups. In either case only delete the older ones and keep the 2 or 3 newest ones.
I also suggest you set LR to place the backups on some other drive connected to your system, like an external drive you use for backing up your system, or to a networked drive, if you have one.
Having backups of anything on the same drive as the original files does you no good if that drive fails, Everything is gone at that point.
Thats really helpful, thank you so much for the quick reply. That must be what they are. I will delete all but a few and take it from there.
Another question if you wouldn't mind helping again?
I am moving my data from a Mac desktop to a mac laptop and don't want to just restore the data from a previous Time Machine backup. I want to set it up as a fresh machine. In relation to Lightroom, is it as simple as just transferring my folder of images and the latest Lightroom catalogue to the new machine, or is it more complex than that?
Yes it is as simple as copying your image files over and the catalog file. BUT make sure you place them in exactly the same PATH. That is the Drive name, Folder name, Subfolder names and so on.
Also you should Sign Out of LR and any other Adobe app you use before installing and signing in on your notebook. That is unless you plan to continue using the Adobe apps on the desktop Mac. You can install all Adobe apps on 2 computers at the same time as long your are the main user and you don't use the same app at the same time on both computers.
Perfect, You are a star. Thanks for that. New to the forum and great to have such great help!