I'm not sure whether this has been noticed but I have found that when adding a song to the same playlist, the application will not be able to recognise that it is the same song if the song is taken from another album such as a compilation, single or another releases. Hence, there will be a duplicate of the exact same song as it seems to only recognise duplicity based on the same album. Could this be solved?
Hope to find a solution.
Updated on 2017-08-22
Hello and thanks for the feedback!
A similar idea has also been suggested here:
Add your votes and comments there please! ;)