So the story I have preserved in my memory about the Warlocks' change of name in 1965 says that it was proximately caused by Phil Lesh's discovery of another local band using the name. I also have it in my head that the existence of these other Warlocks remains mysterious. I would put money on the fact that I am wrong on the latter count, especially.
Just in case, I thought I'd just note that the "chit chat" column of the Oakland Tribune, October 23, 1965, p. 7B makes mention of a local battle of the bands in which one of the competitors is The Warlocks, from Encinal High. (The column also has information on a tiddly winks contest, I shit you not ... no wonder that world was turned upside down by psychedelics. But I digress.)
Anyway, again, I am sure this is well-known, but I didn't know it, so I post it here for my own reference.