Conflict between devices in call log if we have the same Apple ID I have iOS 9.0.2 on an iPhone 5s and my wife has an iPhone 6 with the same iOS version. We have the same Apple ID and we have issue after upgrading the two call logs are the same now. If she has a call I will find it in my log.
Yes, this is part of iCloud which synchronises features across multiple devices which use the same primary Apple ID. If you don't wish this to synchronise, change your primary Apple ID on one of the devices.