An anecdote to try and elevate the thread: got my phone nicked by one of those Marauding Moped Gangs last week so rocking a really shit, cracked iPhone 5 atm. Tried to backup from my previous phone and iCloud decided to upload all of my media - photos and vids - in duplicate, essentially rendering the phone useless for two days.
Anyway, I’ve used 12.71GB of a possible 13GB having deleted about three quarters of said duplicates.