If you are playing a playlist and then add a song that is already on the playlist to the end of the playlist then when the second version of the song plays the now playing symbol shows up by both copies of the song so you can't tell where in the playlist you are actually up to.
Worse than that, when the song finishes and moves on to the next song, instead of moving onto the song after the second copy of the duplicated song it moves onto the song after the first copy creating an endlessly playing loop of all the songs in between the two copies
If you are playing a playlist and then add a song that is already on the playlist to the end of the playlist then when the second version of the song plays the now playing symbol shows up by both copies of the song so you can't tell where in the playlist you are actually up to.
Worse than that, when the song finishes and moves on to the next song, instead of moving onto the song after the second copy of the duplicated song it moves onto the song after the first copy creating an endlessly playing loop of all the songs in between the two copies