I just now looked at my question to see if anyone else knew an answer. Here is what I have found out and I sent the information to the previous person who owned the same lithograph.
I have found out more about our Picasso lithograph. I was able to
> order the Margaret Silberman book (Pour Margaret from Picasso with
> love) from Zurich, and she had an illustration of it and an
> explanation of how she acquired it. (She was the owner of the shop
> where mine was bought sometime between 1961-1965. ) She was friends
> with Picasso and Jacqueline and after Margaret did a favor for
> Picasso, he offered her a choice of 12 pictures of double heads he
> had done. Each was done in a wash. I don't know about this
> technique except it is done with India ink. Anyway, the book also
> listed where our lithograph could be found: Zervos, Christian. Pablo
> Picasso, vol. 19, plate 386. It is a set of 33 volumes. Even though
> ours says Dec. 1, l960, it was actually done Nov. 12, 1960 as were
> the others. Most of the other eleven "Tetes" are on adjacent pages
> in the Zervos book.
> My local art gallery owner-friend is puzzled about what we have. It
> seems there would only be the one original wash picture and then a
> lithograph would have been made in order to sell copies. So I have
> no idea how many lithographs were made of ours or of the other eleven
> heads. (Margaret called it a double head picture.)
> Margaret's book is primarily about Picasso's kindness and generosity
> to her which he often exhibited by giving her drawings.