Validation or program rule for two stages on the same day

Hi all,

Does anyone know how I might set up a validation rule to flag when two program stages happen on the same day (in a tracker program, for one TEI)? I have a tracker program where a person might experience a stage multiple times (ok), but not on the same day (not ok), and there seems to be some duplication in data entry. Would be nice to be able to see quickly where there are two stages on the same day.