@Midnight9746 
Usually, just waiting 30 seconds before you press ready again be enough to almost guarantee that you wont end up with the same teammates again. I did however play a game with two very toxic premades in a ranked match in gold1 or something. I played some more games, went to eat some food and came back 3 hours later to play some more and after some more matches, I got matched with those two again, now in Plat3 haha. Right away in legend selection, I said something like "you are that premade duo who blamed me for losing even though I did 10x your damage and totally carried you the entire match haha", and they answered "yupp sry for that" and we actually had a good game 😉