Hi,
Yes - whoever added the mark would have known that Aarne was a Faberge workmaster, but just gotten the dates wrong.
As for your question about when the Faberge mark was added to an item - I do not know... I would assume that they weren't added by the Masters though I may be wrong! It is not something I have ever considered. If you look through books, you will see that there are quite a few different Fabergé marks around which were used in different Towns.
Fabergé's Moscow Marks:
Postnikov wrote:Signature of Fabergé in Moscow (
always K.ФÐБЕЗЖЕ -
always with the Imperial Eagle (court jeweller´s sign!!) Normaly Fabergé objects made in Moscow are
always without the mark of a master.

Fabergé's St. Petersburg Marks:
Postnikov wrote:The Fabergé marks for St. Petersburg look like that:
Fabergé´s signature with initials (KФ) is often found on St. Petersburg workpieces of the workmasters Nevalainen and Rappoport !!!!
(Both of those with a little extra info from Postnikov!)
Regards,
Piette