If someone were to call me by my username in real life, I would at least want to know who maintained my name. Or any name I have for that matter, my general nickname is often from characters I play the most like "Bene" from Benedikt and "Lafa" from Lafayette. No one really refers to me by my username, mostly because it's more of a title than an actual name anyway. So, yes, I never mind being called by my user in real life or alternative networks, just as long as the identities stay separate from whatever different platform I use. But, if they're pretty much inseparable or have the same origin, then, just calling my by either name is fine.