The circuit is a MCU triggered, capacitor based fan speed controller.
The circuit works fine when a single triac is connected but when both triacs are wired and triggered alternately, any of the triac fails randomly by shorting. Initial load is a 60W incandescent bulb.
The triac gate takes close to 50mA through optocoupler. This seems much higher as the triac has senstive gate which can be triggered by a low power MCU.
MOC3041 Datasheet https://www.fairchildsemi.com/datasheets/MO/MOC3041M.pdf