Unable to copy backups from external drive due to aliases

We don't use the Finder for that purpose.

To restore items from a TM backup, refer to Restore items backed up with Time Machine - Apple Support.

• That document uses "files" and "items" interchangeably. An "item" can be a file, an app, a folder... etc.

If your goal is to restore an item to a location other than its original location (in your case, an external hard disk drive) you can secondary-click the item (two-finger tap, control-click, etc) and choose "Restore <item> to..." and choose the location.

Are you trying to copy Time Machine backups?

Time Machine backups tend not to be easily copied from one drive to another.

Being that copying TM backups can be problematic, perhaps it would be best to simply create a new backup set on the other external drive?

Manipulating files and folders, including aliases, in a backup set may cause disastrous results and infidelity of the data when the backup is most needed. Read that as 'corruption of the backup'.

If you will provide a bit more detail about your process – how are you copying – and the reason for wanting to move these files – what do you hope to accomplish in the end – , perhaps other users can more easily provide focused guidance.

As D.I. Johnson, says you can't drag Time Machine files to a Mac and have them work. This is because Time Machine makes incremental  backups— it records only the things that have changed since the last backup. This means that making backups is really fast, so that they can be done automatically and often. But it also means that sometimes, especially with packages like a Photos Library, the backup only stores a piece of the whole, and the package has to be put together again in order to restore the entire content.  For that you need to Restore the Photos Library package. You can't copy a Time Machine Data file to another drive, because it just doesn't have everything needs to remake the files.

I've tried copying TM files to a new drive. It doesn't work.