Sync frames received back-to-back can lead to wrong adjustment of local clock speed

Especially in network structures that include ring topologies it can happen that a frame that was sent once will be received twice at other devices (e.g. in case the ring state transision from normal to fault or vice versa).
In case that a sync frame (and follow up frame) is received twice in such a situation, this leads to a wrong calculation of the "offset to master" time. The offset to master will get very high and therefore the speed of the local clock is controlled with a wrong assumption.