Battle Hymn when stolen by multiple Goblins only works the first time its used each turn

if you have multiple goblins with battle hymn only the first cast of it each turn nets you any ap or dmg.
all the other goblins can use battle hymn afterwards but nothing happens.
please fix this.

 

Battle hymn doesnt stack, so you can only use it 1 per turn.

 

oh i forgot about the 1+ dmg part/reverie not stacking. ( i posted this when i was sleepy )
but no further ap is gained after the first cast.