Oh! Nevermind.... I see now that it still shows in the hands of the other cacher. You need to make a grab it log on the coin to take the coin out of the hands of the other cacher.
If you can't make a grab it log and it doesn't show up in your collection it probably means it's still in the other cachers collection. If that is the case then they need to goto their collection and drop it back into their inventory, so you can then make a grab it log.