Be sure you understand that when you import using the "Copy" or "Copy as DNG" options- your photos are copied to the folder where they will permanently stay, and where Lightroom makes its references to the files. The "Make a second copy" function is designed to help protect you from loss of files- it creates another set of dated folders with the files grouped by import time (not really useful for long-term backup or restoration of the Lightroom folder structure).
Before you use the operating system to delete the "Second Copies" be 100% certain (using Finder or File Explorer) that you have both the original files where they were imported AND at least one other backup of all your photos on another drive- including the most recent.
So use the OS to check you have the originals AND backups of the 'originals' folders, then use the OS to delete the "Second Copies"
This is very helpful, thank you!
Besides the photo files themselves, are there any other files I would need to delete? In the Download Backups folder, I see a file for the Lightroom Catalog and one for Lightroom Catalog Previews.
Also, can I do this all through the Finder, or is this something that needs to be done through Lightroom somehow?
any other files I would need to delete?
No. (and done in Finder)
You MUST preserve the Lightroom Catalog and all your Original photo files -without fail!
The Catalog contains everything you do, and have ever done, in the Lr software. It does NOT contain your photos.
Be sure you recognize the difference between your Original photo files in folders, and the "Second Copy" folders- they are not the same!
(The Lightroom Catalog Previews folder contains all the previews that Lr creates to display in the library and develop modules. It can be deleted, but only ever consider doing this, with expert advice, if you encounter corruption with the previews.)
Only delete the "Second Copy" folder ( named by the Date and Time of the Import) using Finder- AFTER making archival backups -
Backups of original photos and the Catalog must be on a separate physical hard-drive, as should have been the "Second Copy".
Using different partitions on the same physical drive does not protect against mechanical drive failure.
Am I making it clearer, or harder to understand?
I think the folder structure above can be miss leading the Photo Files "originals are not stored with your Catalog.lrcat and Catalog Previews.lrdata. They reside in the System folder that you have selected when they were imported.
So, there are photos in dated folders for the "second copy". Is there a way, in Lightroom, to search for photos on the basis of import date?
search for photos on the basis of import date?
I do not think this is possible in Lightroom. You can use the Sort option "Added Order" but it does not show a date.
There may be a plug-in available that can pull this information from the Catalog. Something like "Any Filter" Any Filter Lightroom Plugin: Criteria Reference
(Capture Time is certainly searchable.)
(It would not be sensible to store "Added Order" in a file's metadata, as this would change if the image were to be imported to other catalogs on different dates.)