In using 2awg cables (copper). I have connectors rated for al/Cu. Will these end connectors increase the resistance? Or should I look for copper connectors?

If they are rated for CU/AL they should be fine. These are split bolt connectors?

If they are rated for CU/AL they should be fine. These are split bolt connectors?
Actually they have a screw down on the female cable hole.

As I said, if rated for use should be OK.