Regarding Unique Pot Scrolls and Double Miracle Time

So, during miracle time, the chances of ranking up and double ranking up are different? I was always under the impression that you had to get that message just to rank up anyways.

Message only appears for rare -> unique (surprisingly high chance for this to happen, btw. IMO better than cubing epic -> unique)
Epic -> legendary (very low chance, don't count on it happening)
Unique -> legendary