Judging from your description alone, I'd say an algorithm to find appropriate 3-clusters of timestamps would be something like:
compare the three first elements of your sorted lists. Pick the earliest of the three.
Remove the element from its list.
determine difference of that element to the other two first
If both difference are below a "simultaneity&...
When a process or system in which the average, over time, of the physical quantities that describe it coincides with the average calculated over a set of possible states of the process or of the system itself.
I would use an example like the following:
-You would have the similar results after flipping 100 coins as flipping a coin 100 times.
I hope it helps.