Why do we get repeat clues?

festegios

Title pretty much says it, surely once we have collected an upgrade etc it should get removed from the loot pool?

I even got a reward the other day of a double drop of the same upgrade clue….

Please fix this

mariliaribas

I may be mistaken, but I think a while ago you couldn't drop them anymore after upgrading so people that mistakenly added them to the lorebooks collection on alts couldn't add it on their main. This may have been added as a possible solution,but I'm not sure