In cluster environment when the ejb timers based on database store happens if the refresh interval is not small enough this scenario could happen:

Refreshing interval time (R)

Node 1 : creates an ejb timer at time T with expire date E.
Node 2 : tries to cancel an ejb timer within the interval [T, T+ R[

what happens is that any of the nodes could trigger at T + E the timer because the node 2 did not know the existance of the ejb timer node 1 created before the interval of refreshing.

This affects PAM product in cluster environment as we rely on ejb timers for timer features.