Some imply the birthplace birth time or natural phenomenon like Jing Beijing Chen morning Dong winter and Xue snow.
What do you call someone with two first names. Growing up in Birmingham pretty much all of my best friends had double names. You might think Id welcome people using Katharine since I go by two surnames my married name and the one I was born with. A nasab or a kunya is one indivisible element.
In English-speaking context youd normally just call me David and Id al. Double names were not originally hyphenated. As far as having 2 FIRST names.
Cameron Mitchell a man who has two first names that are also two last names. The word namefellow or name-fellow although rather obscure does have exactly the meaning youre after without the connotation of namesake that both people are named after the same person. No one ever called her Claudia.
The mixing of two words or names to create a third word or name is the formation of a Portmanteau. But actually friends call. No I dont want to go by a simple Anne and no there arent any exceptions to that.
Therefore Zine El Abidine Ben Alis last name which is based on a nasab is Ben Ali not Ali. Whenever you know your readers well and want to communicate in a friendly way use first names in the greeting. In business err on the side of formality.
In the case of historical figures it may be the only one of the individuals. In other cases it has been determined by the custom of the country or by some interested segment. Or as Jim said in a comment this can be called having two first names Theres even a Facebook group for people with two first names and an Urban Dictionary entry.