Found a loophole in the climax.
There are 2 killers in each movie, and it's quite known that both the movies have different killers. But the problem is that if the person A is the killer in movie A, there are no scenes of the person who is the killer in the movie B, in the ending final scenes.
Same in the movie B, the killer is the person B, and the, final scenes won't involve the person A.
I hope I can explain better but I don't want to spoil the movie. You'll understand it better if you'll see the movie and then read this.