Subscription event firing twice simultaneously

I am implementing some TOFF logic in my application.

I have a  Thing with a subscription listening to some state tags in an opc server. I have to calculate the final state based on this. S

ometimes two states change simultaneously firing the event twice at the same time which i do not want because it executes the change state logic twice  in parallel in different processors obtaining the same result twice and firing the subscripiton listening if the state has changed to fire twice simultaneously despite in practice having only one change.

Is it possible to force  the subscription to only execute in a single processor so that the second firing is after the first instead of simlutaneous?