I take that to mean 1 pepper in the boil and then another pepper after fermentation, like when you would dry hop. That sounds like plenty of habanero to me, never underestimate the power of a habanero. Taste it after each addition and you can always add more if you want, but you can't take it out if you add too much.
And just a word of caution: if you're cutting up the pepper (and you should to get the flavor and heat out of it), wear disposable rubber gloves while handling the pepper.