Archelous and Hercules do sound the same, I expect thats why they have been grouped together but they arent the same
Found this on a website
"The most remarkable instance of multiple dedication was, however, at Oropus, where the altar was divided into five parts, one dedicated to Heracles, Zeus and Paean Apollo, a second to heroes and their wives, a third to Hestia, Hermes, Amphiaraus and the children of Amphilochus, a fourth to Aphrodite Panacea, Jason, Health, and Healing Athene, and the fifth to the Nymphs, Pan, and the rivers Archelous and Cephissus "

So Archelous seems to be a "pure" greek name in its own right, the name of a river, or river deity. Your ancestors father must have been quite scholarly