The now abolished
Canadian long gun registry required all firearms to be register.
I know Lee Enfield's with their original and sometimes redondant same serial numbers often cause the person assisting in the registration to be quite confused.
So like Warren said, it is possible a previous owner decided to have a couple more numbers added in a similar font to avoid defacing it further more.
I don't remember but i don't think a certain number of digits were required but there was a great deal of confusion and lack of knowledge at that time, by the persons doing the registration.
I was personally told that it was impossible that a Ross rifle serial number be on the wood butt stock... no amount of arguing made any difference.