Unidentified Opera Signature

[nyr134]

I recently purchased a collection of old librettos from the Metropolitan Opera.  Inside one of them (Aida) were the clear signatures of Arturo Toscanini and Adamo Didur.   There is also this unreadable signature.   In 1908, Toscanini conducted and Didur was in the cast, so perhaps this signature belongs to another cast member.  Any ideas?  Thanks.

[lux.ra_14]

Tough one. Some other cast names are in this link, but nothing jumps out as a match:

https://mahlerfoundation.org/mahler/contemporaries/adamo-didur/ 

[bulkcover]

Metropolitan Opera in years 1903-1908 were headed by Heinrich Conried and from 1908 to 1935 by Giulio Gatti-Casazza......
any of the most noted singers of the era appeared at the Met under Gatti-Casazza's leadership, including sopranos Rosa Ponselle, Elisabeth Rethberg, Maria Jeritza, Emmy Destinn, Frances Alda, Frida Leider, Amelita Galli-Curci, Bernice de Pasquali, and Lily Pons; tenors Jacques Urlus, Giovanni Martinelli, Beniamino Gigli, Giacomo Lauri-Volpi, and Lauritz Melchior; baritones Titta Ruffo, Giuseppe De Luca, Pasquale Amato, and Lawrence Tibbett; and basses Friedrich Schorr, Feodor Chaliapin, Jose Mardones, Tancredi Pasero and Ezio Pinza—among many others.
Toscanini served as the Met's principal conductor (but with no official title) from 1908 to 1915.

You might need to look through the event programs of Metropolitan Opera of 1908 and to hunt the names from there...
Signature is so unclear, that even initials are under the question... P? G?

[nyr134]

The stage manager for the 1908 production of Aida was Jules Speck.  Perhaps that is his signature?