Calm down, AP
Q. Which sentence is correct? "When that happens, it can look like one is stepping on the others' toes." Or: "When that happens, it can look like one is stepping on the other's toes." – from Liverpool, N.Y. on Mon, Sep 28, 2015
A. The second.
Along with "did you look it up?" and "no, really -- did you look it up?" and "whichever you want," let's suggest another stock answer for Ask the Editor questions: "Yes."
Maybe more precisely: "Both, but they're each correct about a different thing. Which one did you have in mind?" The first has you (sorry, "one") stepping on more than one set of toes; the second has only one other to worry about the toes of.
The Stylebook doesn't actually have to rule on every question that comes down the pike. It's kind of the editors not to make fun of the really silly ones, but they'd give a better impression of their work -- and avoid turning the study of "style" into a nightmare of random choices -- if they discarded a few of them and gave more sensible answers to others. And yes, "that's not a style question" is a fine answer, too.