It will be reassuring if both are seen at the same time. They are approaching the age where one or both will wander off and move northward. The last eaglet in the area of the nest has been reported between April 27 and June 10, so it is quite variable. Part of the problem in pinning the date down is the lack of observers as they spend less time visible near the nest as they gain hunting skills.
Agree that any sightings should be reported, whether singly or both. The date of disappearance of adults is also of interest.