Having an identical social media handle on all the platforms is awesome. That way they are easy to remember both for you and your followers and they look nice and clean once you present them to someone like in a resume or business card.
Depending on how quickly you register and how massive the site has already become user-wise, you might have encountered a problem - when registering, your selected username might already be taken. Obviously, in this case, you go with another, that is different than you would normally use. How does it affect other usernames you use?
1) Do you not care about that so much and leave as they are?
2) Do you change others (if possible) to the recent one you created so they all are the same?
3) Or maybe you picked up a unique enough handle years ago or you have born with a unique enough name/surname?