Security Update 2020-003 10.13.1
App store says security update above is available but this has already been installed. Does it need to be reinstalled?
iMac 21.5″, macOS 10.13
Yes, a few days after the Security Update 2020-003 was released, Apple released an updated version,
and to make it look like they didn't mess up they gave it he same name as the earlier one.