QF is another one at the moment - merely because of the time it takes to shift all planes over to the new identity.
At one time, they did have a blue/white 747 with one of the BA
world tails, but it was the exception, rather than the rule. At another time, they had a few different colour schemes - including the Australia Asia colours, and later the "Australian" brand - which was actually a very clever and eye-catching play on the traditional Qantas kangaroo logo.
While not a dual livery airline, BA
did have a SQ
liveried Concorde in its fleet. BA
on one side, SQ
on the other. It was Alpha-Delta, one of the earlier Concordes in the BA
fleet. It operated under numerous regos too - N94AD (for America), and G-N94AD (for elsewhere).