Hi … i figured out what was happening … In my Dropbox app Avast have created a link to upload my picture safely but in my Gallery app setting i ask to upload automatically my picture to Dropbox when i’m in wi-fi status so Avast upload my picture and also my Gallery … i got a lot of duplicate pictures in my Dropbox … i delete my Avast safe link to Dropbox and now i have no more issues and no more duplicate … the only thing now, i have to make sure my pictures are uploaded to Dropbox before i delete them from my Gallery app … your setting in the Avast was cool (because it delete the original file after the upload) but i don’t need duplicate my picture