Junk Yard · What gets captured
Does copying the same thing twice create two scraps?
Short answer: No. A copy identical to your most recent one isn't added again, so pressing ⌘C twice won't create duplicates. Copy something else in between and it will be saved again.
No. If you copy exactly the same thing as the most recent copy, the Junk Yard doesn't add it again, so pressing ⌘C twice doesn't litter the board with duplicates.
Copying something else in between and then the first item again does create a new scrap, because it's no longer a repeat of the last copy.