Well, “stereo” implies more information because it’s assumed that it is capturing a space with at least two microphones that are specifically placed to capture the differences between left and right. This is obvious in the construction of a “stereo microphone” which will have the 2 (or more!) elements aiming in different directions, as coincident XY or possibly Mid-Side or even a Blumlein pair. These kinds of placement, or even others when using separate microphones, will always have some information in their assigned tracks that is different from the other mic’s track. The digital file wile be larger than that of a mono/single mic recording, and if you would mix those stereo tracks down to a single mono track, it will not sound the same, and you will not be able to recover the stereo tracks from that mono mix, i.e., information will have been lost.
Now, MAYBE, a pair of omni-directional mics in a coincident setup might be very similar to one of the same kind of mic, but it still will have some differences, though likely not much interesting.