The problem is that there are no good answers to these questions, even if you've decided to standardize on one or two steps, because everyone has different length legs, and some people pace by simply walking whilst others pace by taking exaggerated steps.
Many clues will have pace calibration legs, or other subtle hints, so you can calibrate one pace of the hider's to one of your paces, (see below for a description of pace calibration legs), and you won't have to know or guess what the hider thought a pace was, and how long their legs are, rendering the question moot. If they don't, you will just have to go by feel, or try some of the various definitions and hope your pace is similar to that of the hider's.
For what it's worth, even the dictionary is unclear as to whether a pace is one or two steps. It goes on to define it in terms of various lengths of measure (76cm, 5 English feet, 58.1 English inches), but I doubt any clue writers are thinking along these lines (but who knows :-)).
Finally, an informal survey was done on the Letterbox-USA talk list. 80% of those who had an opinion felt a pace was the same as a single step, i.e., the footfall of either foot, so you can use that if you have nothing else to go on, and as a clue writer, it might make sense to use this as a default.