-They are never seen in the same scene.
-Bell says, "sometimes when I read these deaths in the paper I laugh to" towards his younger partner. Maybe a sign that he finds death simple? Or just a contrast to his younger more violence accepting partner.
-he went back to the crime scene, right after they discussed, "why would chigruh go back to the crime scene?" and it seemed like bell had an idea why but never says.
-he sat in the same chair and drank the same milk looking at the same reflection. (back at the same crime scene again?) and then says, "I feel like I am in his place." Maybe a clue to the link?
-when Chigruh went in the middle of the night with those two deputies to the mexican shooting in the middle of the field and killed them. It seemed weird that two deputies would lead Chigruh to that crime scene.
-bell told someone (I forgot) about how they slaughter cattle now, and he knew a lot about the compressed cattle rod.
-The person that Chigruh pulled over in the beggining while in the cop car, seemed pretty accepting of him, is it because he really looked like bell?
-Chigruh always knew where Moss was(even after he got rid of the transmitter), and that scene where the Wife hesitates about telling Bell where Moss is, but then does it (we assume) made it seem like she was actually telling Chigruh
-At the end Bell was retired, maybe because he got the money? That he found when he returned to the scene.
-The scene where Bell was driving up to the mexican fight at the motel seemed a little odd, like Bell was dissapointed he didn't get to be the one responsible for his death.
But, I know this is wrong. Because, the movie is to well made to have some cheesy twist and at the beggining Chigruh was being arrested, wouldn't make since if it was Bell...
And also, I think every movie I see has atleast one character that is acctually two... damn fight club.