A very simple change to the forever prayer: Do not allow a character to appear more than once in the prayer. If you refuse to accept a character, they are removed from the pool entirely. Now if you think that makes getting other characters too easy because there are less in the pool, hear me out.
This kind of system can make the choice of accepting or declining a character much more meaningful. Think of it like this: "Oh! A new character appeared, one you don't have. But a better one may be out there. Do you choose to accept this one? Or do you want to increase your chances of a better one possibly?"
Getting dupes just wastes a day and is a flaw in what the forever prayer is all about: Getting any character you want. Yeah, you have to deal with a pool of over 100+ characters. And yes, you may fail to get who you really wanted. But it doesn't help if I keep getting the same characters a bunch of times. And as more and more characters are added to the game, these chances of "getting who you want" become even worse. Just give us this one fix to balance that out.
