Google Play Music users who have large libraries and lots of playlists with a lengthy set of titles know how easy it can be to try to add a song that is already on a playlist. A nice tool to help users avoid duplicating a song being listed twice is a feature in the app that detects duplicates and asks the user whether they really want to add it a second time. Google has added this feature to the Google Play Music Android app this month.
Oddly enough, this feature was only present when using the web version of Google Play Music in the past. A new update for the Android app adds this feature for users trying to build or modify a playlist on their mobile devices. Although this new feature appears to just be getting some attention from users, it appears Google added this back on March 9th, which was two minor updates ago for the Google Play Music app.