Firework rocket effect don't work when launched from dispenser

Firework rocket (hand-made with firestars with effects) don't get their explosion effects when launched from a dispenser if it's the only one single copy of it.

In other words, the game need an exact copy of the launched firework rocket remaining in the dispenser for the explosion animation to work.

To reproduce the issue:
1. make a firework rocket with an effect (exemple put a color).
2. put 2 copy of it in a dispenser
3. power the dispenser with a button: first rocket get its color-explosion effect
4. power the dispenser a 2nd time: the last copy of the rocket will be launched and got 0 explosion effects