I have BT cloud apps on my phone and ipad.
I have backed up all my photos from my ipad onto BT cloud.
my phone now keeps instigating a back from my iphone but these are the same pictures that my ipad backed up.
if i allow my iphone to carry out the back up, with it duplicate all the photos again or just scan for ones that i have not backed up and not making a duplicate.
In my experience it will backup the whole folder, including those files that have already been backed up