Seven, actually. They found hundreds of footprints of various animals, about half of which were too questionable to identify.
Footprints are often identified because they get filled in with a different material than the substrate. One on its own might not be enough for a positive ID, but this is way bigger than "two holes"
I don't know why the press article choose the first image of Figure 4, the second image is much more convincing. (You can see clearly the toes, except the middle one.)
Also, in the bottom center of Figure 1 you it is possible to see that they found 4 footprints in a row, and if you imagine that there are one or two missing footprints they are at the correct distance, like the path of someone waking. (Why there are only right footprints and no left footprints?)
Pure speculation here (plus some experience/training in tracking), but if somebody is walking along a shore with one foot in mud, and the other foot in dirt, they only leave deep impressions on one side. Similarly, if they're walking with one foot in shallow water, and one foot in mud, then one side will erode much faster than the other.
Walking around the edge of a lake, with the lake to the walker’s right, and softer/wetter ground under the right feet?