Going from one shift register to two shift registers I am able to control one shift register with this shift function:

void shift (int pin) {
  shiftOut(ds,shcp,MSBFIRST,pin);  
  digitalWrite(stcp,HIGH);        
  delay(100);
  digitalWrite(stcp,LOW);         
}


but when I move to 2 shift registers it does not add up.. how do I need to adapt this method to make it work with 2 shift registers when I am going from 8 leds to 16 leds?

My second register now just copies the first register.. I want the second register to continue instead of repeat
It sounds like the primary issue is how you've connected the two shift registers.  You just need the bit shifting out of the first one to shift into the second one so they act, together, as one longer shift register.



The example pictured is described in full here, under the heading "Example 2":
http://arduino.cc/en/tutorial/ShiftOut

As Klaus mentioned, you want to first ShiftOut the byte you intend to wind up in the second resister, then ShiftOut the byte for the first register.  This will push your first byte through to the second register.