It is true that the stamp Scott 1 (medio real stamp)doesn’t have an error like the vertical pair imperforated horizontaly (Scott 1b), but we can find other interesting errors. For example double perforations. They’re not as difficult as the Scott 1b, but they’re very elusive.
What’s really interesting about this errors is that they’re human made -the first issue perforations were made manually- that (in my opinion) gives more authenticity to the piece.
