I heared a taped shiur about names given by rav yissachar frand.
he said that the marshal criticized the then somewhat new practice of giving people more than one name.
I also saw in sefer nachlas shivah (the classic sefer on writting shtaros of all types) that the author also expressed surprise at the unusual practice in some places of giving more than one name.
it was also evident to me from this sefer that at that time, when a person’s name was changed due to illness, it was completely changed to a different name. not as we do, which is to add on an additional name before the current name.
also yes, you can find names in tanach and mishnah that are a phrase but it is still a single name.