I have a hard time following complex plots

First, sorry for the late responce..

I just got done watching this for the 2nd time..

There were 2 murders in this movie..

Alan and the Conveience store guy..

Alan killed 3 people, who were un related to each other to make it appear random.

The Conveneience store murderer just would go in and kill some people there, and rob the place..

Now in the last scene where someone holds up the Conveience store, it's not the same guy who has been killing people while robbing them, he is just someone else.

The plot was confusing because it was badly written.

Its that man again!!