Sometimes there are two sets of stairs

Is there ever any difference between stairs? Sometimes I find two on a level. Since you can't travel back up, it seems unlikely that there's branching. They taunt me so. What possibilities lie behind that set of stairs I'll never climb?

When the floors get sufficiently large, multiple sets of stairs appear. This prevents tiresome scouring of the map for the one staircase out of 2500+ tiles of the floor.