It would be called multiple times, once for every actor since they all “began overlapping”.
If you are looking for a specific actor a common way is to try and “cast to” the type you are looking for and continue the logic from there (your actor will also have all its variables and functions as a side effect)
If you are asking about the order in which they would appear - there is no guranteed order (if they are in the exact same frame, which would be very rare unless its on spawn).