I think yug and kaka are partners and they are trying to bring jusyice to Radha by punishing the killer. I think yug is Radha's lover maybe it was one sided like yug like Radha but Radha liked MJ and MJ considers Radha as only friend. Or maybe it was two sided. MJ and yug didn't meet CID before the meeting cud happen Radha died and MJ was sent behind the bars. So yug is out to get his revenge and kaka is a lil less revengy cos he knows the family and feels maybe MJ didn't do the crime or is tring to get evidence against him by siding with him. I think we will have to wait and watch to see what happens with this Bhool bulaiya
Oh Yug being the lover...I really like that thought . I now feel thats probably what it is. As I said if he and kaka were partners in crime then they are both working in opposite directions. Your logic explains why they are both out for revenge and yet kaka seems to have joined hands with MJ to expose RP.