You always get that kind of crap when you try to help someone with grammar or spelling.
It baffles me, really. You’d think they’d just say “thank you” and move on.
If my fly were open, I’d want someone to tell me, but when someone is making making himself look uneducated with bad grammar or misspelling, he reacts to assistance...well, as you saw here.
This is an example of repetitive redundancy.
By the way, your fly is open :)