Mine will do the same thing, especially when everything is up to operating temp and the oil is thinner in the transmission. It doesn't take much drag through from the moving parts to make the disengaged clutch disk want to follow along with the movement when everything is turning free, and with no synchronizers there are only gear teeth to bump along until you pull it into mesh. However, with that said, mine will generally stay mostly stopped if you stop by holding the clutch and leaving the transmission in gear while stopping and then find neutral without lifting the clutch. Once stopped, you can shift to another gear generally without any clashing, except on occasion the high points on the teeth are lined up and you'll have to bump the clutch out slightly or just wait a moment for the teeth to creep past so they will mesh. I'm spoiled with the aux transmission, as I can pop it into neutral, and since there is nothing then connected to the output of the main transmission, it will slip into gear without any major clashing pretty quickly, and then the little bit of extra drag from the intermediate shaft and gears in the aux transmission spinning will slow everything down to a stop much quicker while keeping the clutch depressed. Although if your not patient, you can still get the aux into gear too soon with a satisfying clunk and a small hop forward in the truck....
The key is patience, sometimes a lot of it. The problem described is why many large trucks have a clutch brake that activates when the clutch pedal is fully depressed.
