In reply to kjhhgt76:
In the general case, there is no way to know if two clock transitioned in the same time unit until after that time unit is over.
If we know the transitions occur in the same event region, then we can know they transition in the next event region of the same time unit. It would help to know how there clocks are generated and if there is another common reference clock between them.
It would also help to know what do you plan to do in these two threads as moving them to another event region might cause other issues.