Easy, he admitted to messing up.
Double clutching can reduce wear on the synchro's, if you NEED to do it you're probably dropping to too low a gear. Forcing it in when the speed difference is too great for the synchro's can wear them out. Hopefully the OP didn't damage the gear dogs enough to make it start popping out of gear. Now he needs to double clutch every time into third.
Changing the trans. lube a time or two to get out most of the carnage would be a good idea, at the price of Ford "Honey" for the trans. the lesson will be reinforced enough.
"Rubber Side Down"