Problems will not go away....

That reminds me of the days I drove an old truck with "3 on the tree". If you shifted too fast the linkage would cause both levers to move at the same time resulting in 2 gears engaged at the same time. You had to turn off the truck and reposition the levers by hand. Those were the days!
Was it a late 60's early 70's Ford? My dad had them for his business and every one of them did this....