The “call continuity” module is responsible for rebuilding the queues on the standby server (as it promotes to primary). The queues are rebuilt in the order of which the calls arrived at the PBX. If a call was first answered by a user (or some other service) and then transferred to the queue, it is possible that the order of arrival at the PBX does not match the order of entry to the queue. Realistically, those few calls might be only slightly out of position.
At this time we do have any workaround for this situation. However, this should affect very few calls (<1%) and the impact should be minimal (minor change in order for those few calls). In a future version of the call continuity module we may use call queue entry times for queue reconstruction. Because of some Asterisk limitations this is not as easy as it sounds.
If this issues is a problem for your customers we recommend announcing estimated wait time instead of queue position.