How can I queue in both lanes at the same time?
If you tell to more than one person, for example to hundred people, you can say queue in both lines.
No, you can't, Szaka. Each individual member of the group can still only queue in one line.
Let us not forget the "You" is understood. Assuming the direction is addressed to an individual, one cannot be in two lanes at one time.
Could a really fat person queue in both lanes?
Or both if you have a split personality!
I've changed my mind. "Use both lanes" is OK, but "Queue in both lanes" is not, since I can't.