[Icemage]

Recently my friend's been having problems sticking 2 ballads on himself. I don't know the exact details of what he's been doing, but you seem to know something about ballads not sticking... Could you go into more detail about it? He said that he just buffed melees, then buffed mages, and while the mages would have both songs, he would end up with 1 melee song and 1 mage song.
He's was really confused why, but stopped caring after he couldn't figure it out and after making sure the mages actually got both songs.

Simplest possible explanation:

Songs stick to you based on their "duration remaining". Under normal circumstances, all beneficial bard songs have a base duration of 120 seconds (2 minutes). For each +1 to that song you receive from your instrument, add 10 seconds to that figure.

Whenever you cast a new song, it always sticks to you. However, the game looks at all of your older songs and sees which of the two has less duration remaining, and drops that one to make room for your new song

So if you cast Minuet with a +2 to Minuet instrument, it starts at 140 seconds.
Spend 8 seconds to cast Madrigal with a +2 instrument, and it starts at 140, with Minuet at 132 seconds.

If you immediately cast Ballad at this point, you end up with (8 seconds later):

Minuet at 124 seconds (old)
Madrigal at 132 seconds (old)
Ballad at 120 seconds (new)

Since Ballad is new, it sticks to you, and Minuet (the old song with lowest remaining duration) is dropped, leaving you with Ballad and Madrigal.

Now let's say you cast Ballad II. 8 seconds after starting, you now have:

Madrigal at 124 seconds (old)
Ballad at 112 seconds (old)
Ballad II at 120 seconds (new)

The game will force Ballad I to be dropped from your list, leaving you with Madrigal at 124 seconds and Ballad II at 120 seconds.

If you sing any other song at this point, it will force Ballad II to be dropped (Advancing March, for instance), leaving you with March and Madrigal.

This is why you have to wait 20 seconds when using +2 instruments, as I mentioned in the above post. It gives your melee songs a bit of time to "cool off" so you can keep the Ballads on you while pulling.