The origin of Fabrizio Salani's "AG" monagram

[Koen G]

Ah yes, it is just the same Renoir collection, which Dover likes to republish every now and then.

The AG on the wax seal really sits in between Design 1 (=Renoir) and Design 5. 

Common with Design 1:

• little cap on top of "G"
  
• order of overlap
  

Common with Design 2:

• Top of A
  
• Single-lobed bites out of G
  
• Rounded loop.
  

   

In short, the wax seal is very close to Design 5, but maintains more properties of Renoir (Design 1). This leads me to hypothesize that the design of the stamp used to make the wax seal was post-Renoir, and closely related to Design 5. But everything remains possible - maybe both Renoir and Design 5 are based on an older seal.