If you’ve been logging in to draft frequently enough (twice a day?) then you should have two legendaries by now. If you redraft something and it becomes weaker monsters (e.g. 6* down to 4*) then what happened is you actually got a “lucky draw” where you were meant to get a certain strength of monsters but it got upgraded to be stronger ones. Redrafting these lucky draws makes it revert to how it should have been. It’s hard to know if you got a “lucky draw” but if you can learn roughly when you are meant to get your first legendary and when the others come then you might have a good idea if what you have in front of you is an extra one.
I see. I wasn’t aware of those facts.