Ah, I can see why you might want that then. Because the easiest solution to that puzzle, at the moment, is just to DROP ALL on the ground and, providing you've got the item, then you've solved it.
There are a few ways around it, I think...
One would be to use a counter that counts how many objects you've dropped and stops you from dropping any more when the limit of 2 is reached. You'd need to pick up one of the objects (decresing the counter) to allow you to drop more. That would work fine, I think.
Another would be to use the GIVE object, to give each item you're trying in turn. Maybe this could be linked to the container system and a counter, again, to make sure you can only give him two. The "container" could be a "large wooden table" in front of the Riddle-man.
GIVE ROCK... "The man takes it off you and puts it on the table in front of him."
EXAMINE TABLE... "On the table is: A rock and a handle."
GET ROCK... "You get the rock."
GIVE ROD... "The man takes it off you and puts it on the table in front of him."
"Yes, that's right," says the man.... etc.... etc....