Setting pressures on dual body regulator?

[KindofBlues71]

I just started kegging and was wondering what the rule of thumb is for setting pressures on a dual body regulator? I have this regulator for Northern Brewer:

Is it best to set the higher pressure on the regulator body closest to the tank (right side in the above pic) and lower pressures on the other one (left side in pic)?

Also, I bought the ball lock gas connector kit (tubing, gas QD and swivel nut) from NB as well and was wondering if anyone knew the tubing I.D. size? The product description says 1/4" swivel nuts, so does that mean the tubing is 1/4" I.D.? I thought gas tubing was usually 5/16" I.D.

 

[MichaelBrock]

It doesn't make any difference in this case which of the pressures you put on which gauge. The size of the swivel nut is not an indication of the tubing diameter. All of my connections are 1/4" swivel nuts and my gas tubing is 5/16" ID.