are you getting the same odds? as if so I would not worry to much, worst case scenario is that they score 8, then you get a push, but Grumpy gets a win, so no great loss.
Under 8 both win, over 8 both lose, chances of it being 8 runs exact is quite small I would imagine, if you really did want to cover it, put a small side wager on 8 runs scored, that way you are covered all ways