When combining 5 runes to get a higher-tier one, can you get runes that you already have unlocked 9 of, or are you guaranteed to get a rune that you are still missing?

Everyone who played jungler should know the situation: Mid can't pull for whichever reason - for example on account of being Fizz - so someone else attacks once and runs away, you as jungler start punching the golem and then it resets while all your cooldowns are down and you end up taking twice ...