Let's imagine we have two different structures for the same compound, and that structure 1 has the lower energy and structure 2 has the higher energy. If you consider the potential energy surface of all potential atomic configurations, then each of these structures sits at a local minimum, and the minimum associated with structure 1 is lower in energy than the minimum associated with structure 2. I am also going to assume, for simplicity, that structure 1 is the global minimum, so it is the ground state structure.
What does this mean regarding the experimental synthesis of these structures? Structure 1, which is the global minimum, is the most stable structure. What this means is that it will typically be easier to synthesize, and if you wait long enough, any structure of that compound will eventually turn into structure 1. However, it may still possible to synthesize structure 2 experimentally. Depending on your synthesis route, you can create structure 2, which is then "stuck" in that minimum and, even though the minimum of structure 1 is lower in energy, there is an energy barrier to get there. A very famous example of this is carbon structures. The ground state structure of carbon is graphite (my structure 1), but you can also find diamond (my structure 2). In this case, diamond is synthesized at high pressures (where it is actually the lowest energy structure), and then releasing pressure leaves it stuck at its local minimum of energy. Even though diamond is not the lowest energy structure at ambient pressure, it is a structure that carbon can adopt.
What does all this mean for your question? I guess there could be two things going on here:
Both structures can be synthesized. The old experiment happened to synthesize a higher energy but locally stable structure (think diamond), and the new experiment has synthesized the true ground state (think graphite). In this case, I would not call any of the two structures hypothetical, as they have both been confirmed experimentally.
Another option that always needs to be considered is that one of the experiments is wrong.