Flyspecking the Italy 100 Lire 1945 issue
This stamp comes from 2 plates
The second plate has a notch on top RHS corner
This stamp comes in a variety of preforations
so keep one as a template and use others to compare
OK the Plate Number 1 No notch

deatil Plate 1 no notch

Plate 2 spot the notch! :)

Thanks to Tony Clayton.