I don't see why they wouldn't be able to tell the difference between one person and the next by scent and temps. The question to me, really, is whether they could or would retain any information related to that to be able to identify the same person next time. What kind of memory do snakes have? Obviously they can remember a particular prey item as being a favorite and identify it by smell/temp, so it's possible they could use the same memory type to identify handlers, but their brains are so small and so focused on enabling them to be snakey that it's hard to say for certain that they'd have the capacity for that. I'd be inclined to guess that they might store information on one or two regular handlers and identify other humans by "not prey/large mammal/not handler" type categorizing.