Why duo queue never touches your login
Duo queue is the play-together method: the booster stays on their own account and joins your party, so the two of you queue ranked matches side by side. Nothing is ever shared — no password, no appear-offline pilot on your account, no VPN riding your session — because you are literally the one logged in and playing. Matchmaking sees a party rather than a single account, which is why every game shows your own personal participation in the match history. If account safety is the reason you're comparing methods, this is the one that removes the login-sharing question entirely.