Arms of commercial enterprises normally have supporters.

The story of the Mozambique Company Forgeries 
 

Genuine, comb perf.

Probable forgery, 11.5 line perf.

Only about one percent of the Mozambique Company stamps of the 1902 arms issue have the true 11½ line perforation, and there are design differences between them and the comb perforated stamps. This and the existence of copies with genuine postmarks suggest that these stamps are forgeries aimed at the postal authorities, which is the reason for showing here postally used stamps.
 

Genuine, Lisbon overprint, 13mm

Forgery, local overprint, 14mm

The introduction of the REPUBLICA overprint in 1911 forced the forgerer to forge that as well. He used the same type of letters as the local overprint (which was the first used), but there is a difference of about one millimetre in length between the forged and the genuine overprints.
 

The open book is a typical charge on arms of universities.