It looks like you are using feathers so the weight should be pretty close to the same as the fletched ones. Especially considering you do it the way I do it. You left the base of the fletchings and glue on and just shaved the fletchings off. I bet your FOC for that arrows is almost identical.

How far were you shooting those two arrows from? It doesn't get much better than that! Bare shaft testing is really designed for finger shooters, keep that in mind. But it can tell you some things even when using a release.

Like Arthur said, pay no attention to the angle of the arrows. It means very little for your set up. You are only concerned with WHERE the arrows hit in relationship to each other. If you can't seem to bring them together with minor rest or nock adjustment then start looking at spine. Providing you have well matched arrows.

I also agree if that was at 10 yards move back to 15 or 20 and see what happens. And remember this is based on how well you can shoot. Shooting arrows with no fletchings on them is very non forgiving and requires VERY good form. If you shoot them at 20 yards and they are within a few inches of each other I personally would leave it alone. And remember, this is considering you can consistently shoot 2 inch groups at 20 yards. If you can't don't expect to be able to do it with one fletched arrow and one unfletched arrow. Many people try to tune better than they can shoot and end up going insane over it.

Good luck,
Paul