The duration prioritization doesn't seem to be functioning, at least with respect to Unstable Affliction.  UA (as of 7.1) now applies as multiple seperate debuffs on the target.  I have my icon set to prioritize high duration:  http://puu.sh/tqezm/eb9e4719c4.png.  However, when I chain-cast multiple UAs onto the target, the timer shown is for the first one applied (the lowest duration) until it expires, then it shows the remaining duration on the next one applies, then the next, and so on.

Now, the Normal Duration tooltip seems to suggest that these options may only apply when tracking multiple different debuffs, but if such is the case, these settings seem rational to apply to even multiple instances of the same debuff.

Posted by CurseForge user Kaedys | Imported from CurseForge issue #1368 | Raw

Looks like duration priority wasn't working at all. Fixed now.

Posted by CurseForge user Cybeloras