This is an Applescript which accounts for the primitive interface and slow execution.

What is it and what does it do?
Let me paint a scenario.
You painstakingly select a lot of files in order to copy them to another disk, but an error message comes up, one or more of the files in the list already exist at the destination. While you are trying to figure out which file(s) and what to do about it, the files you selected are unselect. Sigh. Not only do you have to select all the files again, you still have to figure out which ones should not be copied. Well this program could help you reselect the files, if you had some forethought.

System requirements and installation
You need to have Applescript installed to run this program.
Installation is simple, just put the programs where you can find them.

Operation
When you have files selected run Save selection
To have this selection restored, run Restore selection.