Any reason you using random (10) for 3 items?...why not random (3)?...
yes, that will get kinda messy...and you would only be able to have 10 drop items max, with your example...
If you have the paid version you can use a family
and the command spawn "name of family" will create a random item from that family...
if using free version, its probably better to use one sprite, call it drops, and put each drop item into that as a seperate animation frame, set animation speed to 0.
Then in game
monster spawn drops sprite, set frame number to int(random(10)) if you have ten items...