Authenticating a Signed Pavarotti Photograph

Some years ago we acquired this signed photograph of Luciano Pavarotti, probably the most beloved tenor of the 20th century.

This photograph is signed by Pavarotti and personalized "A Darren", with the year "2009".

How does a personalization affect our ability to authenticate this photograph, and more importantly, ascertain if Pavarotti's signature is genuine?

Anything added to a collectible item has the potential to depreciate its resale value, as well as its general value for collectors. The fact that someone would allow the name of a non-celebrity to be added to this photograph, increases the credibility of the celebrity's signature on the photograph.

Furthermore, based on the penmanship of the personalization differing from that of the signature, we can imagine that Pavarotti took his time to spell out "A Darren".

It is highly unlikely that someone who is forging a celebrity's signature would add the name of an unknown person, as this reduces the chances that someone would want to purchase the photograph. The personalization, also, of course implies that the signature was obtained for personal use, so there is little reason to suspect a person of forging a signature for their private collection.

Here's the information on the photograph itself: