Duplicate reposts aren't deduplicated, cause playback bugs

[mistydemeo]

Soundnode doesn't deduplicate duplicate reposts. If you're following more than one user who reposts the same song, the song will appear multiple times in your stream. (The official Soundcloud webapp, by comparison, only includes the most recent repost of the song in the stream and clears out all duplicates.)

There is also some unexpected behaviour if the user tries to interact with extra occurrences of the song. For example, while the song will appear twice in the stream, trying to play/like/etc. the second occurrence of the song will cause Soundnode to act as though the user interacted with the first occurrence. In the below screenshot, Soundnode is showing the playback indicator on the first occurrence of the song even though I actually clicked play on the second.

Similarly, when the first repost finishes playing, it will look like Soundnode looped back to the same song when it's playing the next repost.

This was tested using the release version of Soundnode 0.5.7 on Mac OS X 10.10. There's no relevant information in the debug log.

[mistydemeo]

I wondered if it would loop the tracks infinitely, but it doesn't look like that's the case. While clicking play on the second track counts as clicking play on the first, it will only play as many times as there are reposts. e.g. when clicking on the second repost, it will play the song twice, then continue on through my stream.