Spells: Selo's Assonant Strane not working as it should

[Lazortag]

When I use selo's assonant strane (using a lute) on a group of mobs and then use Denon's Disruptive Dischord (using a horn) on that same group, the mobs all begin to move about twice is fast. This is clearly not working as intended. Denon's Disruptive Dischord shouldn't override a completely different song, nor should switching instruments.