IK/FK Rig Problem

While following Alan's IK/FK rig tutorial I came across a problem. When I was making the second wrist joint and ataching it to the first wrist, the first wrist joint still has influence over the mesh wrist. Yet when Alan made the second wrist and parent it to the first wrist, the second wrist has influence over the wrist mesh.

I can fix it, but I was wondering what did I do wrong when duplicating the mesh, if anyone knows please help me.

Here is the image that shows my problem when rotating the second wrist joint.