Deadhead,
It's common knowledge, not only for the dash, but for any turbine engine that once you select fuel off that you would never reselect it back to on for any known reason until the engine has stopped.
However, the typical engine shut-down sequence for the Dash 8 is that when the engines have been run (condition levers max), the condition levers are moved to start/feather for 30 seconds prior to selecting fuel off. There is a detent between each position (min, start/feather and fuel off), but it is VERY easy to pull the condition levers out over both the detents and accidently go directly to fuel off and miss start/feather altogether. It's also VERY easy to go "oops" and reselect start/feather in an effort to recover the situation, with potentially expensive results.
At the very least you get an impressive smokescreen good enough to turn out the firies, at worst you melt metal.
Lots have done it, and no doubt more will.