That seems pretty interesting. Was that because of the war that they did that? Does anyone have any history on this subject? Thanks for letting me know what this is!
"in 1943, new plates were not issued due to the metal shortage caused by World War II. Instead, motorists were issued pairs of black on red metal tabs to validate their 1942 plates for 1943. According to the accompanying instructions, these tabs were to be attached to the 1942 plate at the top left bolt hole; in practice, however, it seems that motorists attached the tabs at either upper bolt hole as they saw fit. The tab featured an embossed keystone outline with the year "43" inside, and a still smaller "3-31-44" expiration date and an engraved serial number. New plates were issued for 1944"