Is there a key for Cancelling a multiple selection?
No Single-tapping option to toggle selection type + Apple’s introduction of double-tapping suggests a good cancel would be double-tapping shift
Or double tapping option?
I wonder though if it should just “pop” the last selection, this would then also work as an undo for ⌃W (select next word) which is sometimes requested. But it might be a little tedious if you have many carets/selections.
That would be nice. ⌃W would be greatly enhanced is ⇧⇧ popped one selection off the stack. Likewise any multiple cursors created by a single operation (be in option tap or ⌘⌥-F) would work as expected when the user double tapped the shift key.