2 12/2 NM cables in one hole through top plate into attic cellulose

Hi I have recently found a 12/2 cable running in my return air duct that is just connected with wire caps and not in a box. Someone who remodeled the house moved the receptacle a foot to the left and just wire nutted the wires that used to go into the old recptacle and pushed them back into the return duct. The air return duct is a stud bay being used as a return air duct that goes down into the lower floor joists. I have a small stud bay directly to the side with a two gang switchbox. This is were the cable originates from and then travels through a hole in the stud and into the air retun stud bay where the put the new recptcle, then a foot down the line it is junctioned with the wire nuts then continues up a stud and out the top of the bay into the attic. I would like to bypass the air return by pulling the cable back into the neighboring bay that has a 2 gang switchbox and put the receptacle there. Then cut the cable that comes out of the top of the air retun duct and remove that unused cable out of the return if possible. I would then fish a cable down the switchbox studbay to the receptacle and junction the the circuit in the attic. I have found where the cables exit the switchbox studbay and one of the holes has room for one more cable to slide in. Is it ok to put (2) 12/2 cables that are on seperate circuits through the same hole in the top plate if it will go up into/through cellulose insulation? They will go seperate ways immediatley after exiting the hole in the toplate.