These functions are used to mark/check if a key of our own has been used to spend (and only for avoid-reuse wallets), which has nothing to do with the destination/address itself. Give them more accurate names to avoid confusion.
-BEGIN VERIFY SCRIPT- sed -i -e 's/UsedDestination/SpentKey/g' $(git grep -l 'UsedDestination' ./src) -END VERIFY SCRIPT-