As far as the precap is concerned,
Firstly, Rajat tried hard to save her. Anu was already falling from the cliff, so had he been a duplicate Rajat, he would have walked off and Anu would have fallen.
Secondly, In the promo, we can clearly see blood on Rajat's Forehead indicating that he may have indulged into some fight making him injured. So being injured, he may not be able to hold Anu's Hand firmly and that may have lead to Anu's fall. That doesnt mean he purposefully left Anu's hand.
Thirdly, the smile of Rajat was not wicked one but one of Relief. When he hold her hand he is relieved that he will be able to save her. But suddenly when Rajat starting losing grip of her hand, Anu Expression might have changed(That expression was not for Rajat Wicked Smile). And then finally when he leaves the hand, he is very disappointed. If he would have been some 'Behrupiya', he would have been happy.
So until anything is confirmed, Please dont spread negativity againt out dear Rajju.