Mystery tag by ID plate?

On my 1957 Cub Lo-boy (sn # 5624) there appears to have been some sort of ID tag to the upper left of the Serial # ID plate. It's not there now, but the imprint is still in the paint. It was oval, about 1" high X 2" wide. There are 2 rivets that held it on, they match the ones on the Serial # tag, at the upper left and lower right corners of this tag. Does anyone know what this tag was for ?

Tom,

I'm only guessing but the local governments bought alot of Cubs for parks etc. Could be an inventory tag some government agency put on then removed when it was sold.

Also in the old days, alot of dealers would put tags on with their parts supply numbers, so they were the first ones you would think of. Usually they were stickers, though.