I think that the episode "Crocoduel" where Purple Tigress was introduced was a very crucial episode, and it showed us a rule when it comes to freeing akumas or amoks. An object needs to be in its official condition for the akuma or amok to escape. Meaning the same has happened with the rings

MEANING that most likely the twin rings were welded together while the making of adrien, and were seperated after adrien was created, and not because they were smart enough and wanted to prevent this form happening but because they both wanted to be able to control adrien

basically in one of the episodes gabriel ordered adrien to never see marinette again with the twin ring, and nathalie gave him the opposite order, meaning both of the rings can control adrien, which is only possible if the amok is split between them just like in crocoduel with the akuma