Yes they're different names, but they have had a tendency to switch back and forth, mostly from Clarke to Clark but sometimes the other way. For instance, my 8ggrandfather Richard Clarke had a bunch of children mostly Clarkes but my 7ggrandfather was Samuel Clark (or at least that's what I show and certainly by my 5ggrandfather it was another Samuel Clark. (I suppose I ought to go see if I've entered my Clark line here back that far and if so what the tree here has. for the spellings