>>102686093Then they're idiots.
Relper specifically didn't call Dean by his name until the last minute, at which point he called him Rusty.
Relper doesn't seem particuarly good at being encouraging (and he's voiced by Rhys Darby, who has been typecast into a bumbling fool stronger than most voice actors in history), so the odds are much better that he simply thought Dean was Rusty.
In addition, part of Dean's appreciation for his father comes from the fact that he spent the night with Relper, trying to help him, only for Relper to mistake him for his father. Seeing that his father used to be a lot more compassionate than he is (in addition to Rusty displaying true diplomacy and parenting skills), and seeing that Jonas was even more obviously a monster.
People might not want to think that, because it complicates the brotherhood/relationship between Rusty and the Monarch and doesn't make them true twins/brothers.
But that doesn't make Rusty being a clone any less likely.