I hardly can imagine this could happen by avast passwords by joining to synchronization and I would say it is impossible to be done repeatedly. When you join device to synchronization all records of that device are sent to other devices as well as records from other device are received by the device. We are not doing any merge on accounts being synchronized so if you have had 25 accounts on iPhone and 25 accounts on PC you will end up with 50 on both devices. We know it is not ideal, but we can’t decide which of those are valid and which are obsolete so we are letting users to decide and manage their accounts by their own. We could use decision based on password timestamp and we are still considering it but we have nothing like that implemented yet.