does anyone answer a spotify question for me

if I'm on premium and have downloaded a playlist of say 20 songs to listen too offline, and then I add another 5 songs to this playlist the following week, if I wanted them all available offline if I downloaded the playlist again would it duplicate the other 20 songs a second time? or would it automatically just add the 5 new songs added

It would only add the new songs. Once a playlist is marked as available offline it will just keep syncing new songs to any device that downloads the playlist.

excellent that's all I needed to know cheers