Not sure. I don't think they have ever referred to him as "Fred" or "Harris" so it's up to debate if they do.

Since when I created Ham-Boy I had in my mind of him being "a young Clark Kent growing up to be Spider-Man" I'd think that HB would not be all that forth coming about his real name at first but as I think HB thinks of the Juniors as his friends so he might have revealed this fact by this point in time. But then I not since he might not of since he might of not be sure that they could keep the secret. (Loose lips sink ships).

There are only a handful of people that know that Fred Harris & Ham-Boy are the same person: Fred's Family: Janis Harris-Smith (His mom), Jordan Smith (his step-father), Al Harris (his grandfather), his best friend growing up, Betty Stevens (she's Jasper Stevens/Kid Produce's cousin) & Visionary. I've built up in my mind that Fred would have told Vish his real name since Fred respects him & feels good enough to trust him with his piece of information.

I hope this answers your question.

~Brian/L!~