This. For big group workouts in college we would have a long line of us doing that. Depending on the workout, we might end up bunching up a bit at the end, so the guys who started in the back and moved up ran a bit quick, but other than that it works well. We'd also sometimes start in broken up groups and other times it would just naturally happen as some people ran faster and others slower.
I guess I don't know the exact situation here, but assuming both groups are using a public track that has open hours, then no, this other group should not be forced to run into lane 3 to pass your group. When they yell "track" you should all move into lane 1 to let them pass in lane 2. Common courtesy.
Now if your'e a college team and this is your home track, it's a different story. They'd be "visitors" on your track and you would have priority to workout the way you want.
This topic makes me miss college workouts. Since graduating, if me and one other guy are doing a whole workout together on the track, then that is a great day. Happens pretty rarely and I miss the big group workouts. There were things I could do in that setting that I never would have done solo. (This can be a negative aspect too if you end up pushing too hard, but usually it helped rather than hurt.)