Vanahk's Staff

This an unique staff dropped by Lieutenant Vanahk in the Yatendi Canyons.

Weapon Stats
Staff
 * Energy +10
 * Dark damage: 11-22 (Req 9 Blood Magic)
 * Halves skill recharge of spells (20% chance)
 * Halves casting time of Blood Magic spells (20% chance)
 * Halves casting time of Blood Magic spells (20% chance)
 * Health +30

do these half casting times stack?