what bug is that exactly?
That you can stack multiple copies of the same skill to get -0.8 total skill time for each of them. (Instead of -0.2 for both skills?).
Yeah sure you need 4x Quick Shot lv 4 but lowering it to basically 0,3 seconds destroyed the entire game balance. + there is a tunic that is lit. useless now since it does -0.25 when you equip a single skill.
Entire meta game is dominated by monk rope.