Being as cut and paste is not an option I copy and paste from Gallery to a folder in Music or doco or pictures, then when I next go to gallery they have been duplicated which I delete, it seems that 'Gallery' scans all folders and then adds pics to gallery they are not edited at this stage. there must be an option to prevent this but I can't find it. thanks for the links I will check them out.
From the link you provided. I have altered a default setting from never discard duplicate to discard after 1 week worth a try.