Restoring to another iPhone Do I need to reset my iPhone before restoring a backup of a different phone?  Eg swapping phones with partner. I have done both backups but not sure if I need to restore each phone first
General recommendation from Apple is to reset your device before restoring from backup.

iCloud: Restore or set up iOS devices from an iCloud backup


  
  Go to Settings > General > Reset, then tap “Erase All Content and Settings.”
  


Restoring from an iTunes or iCloud backup when a later version of iOS is required


  
  Erase your iOS device: Tap Settings > General > Reset > Erase All Content and Settings. After your device is erased, it restarts and you'll see the Hello screen in the Setup Assistant.
  
  
  Now you should be able to set up your device again, and select a backup to restore from.