I re-purchase songs I've already downloaded.
Sometimes I'm NOT prompted that I've already purchased a song and I re-purchase it. Very frustrating - this should be addressed with several layers of warnings, visually on the track listing, when adding it, or a final warning before purchases.
This is so frustrating. Often the same song is sold by multiple labels or under different releases. I totally understand that these are different sellers offering these products, but as a consumer, the experience sucks.