Adding second Shift register

I need a little help with my coding. But before I start, i should mention that i have no prior knowledge of coding. But I did found this code that I like, it similiar to the audi style sequential lights. So one turns on stay lit and follow by the other 7 on the shift register. Now what I like to do is add a second shift register to it to have a total of 16 LEDs. I’ve tweak the code around alot but like mention with no knowledge of it I was just wasting time. So would anyone know what else to add to it so the the other 8 led on the second shift reg. Will light up right after the first one than cut out all at once?

int latchPin = 5;
int clockPin = 6;
int dataPin = 4;
 
byte leds = 0;
 
void setup() 
{
  pinMode(latchPin, OUTPUT);
  pinMode(dataPin, OUTPUT);  
  pinMode(clockPin, OUTPUT);
}
 
void loop() 
{
  leds = 0;
  updateShiftRegister();
  delay(500);
  for (int i = 0; i < 8; i++)
  {
    bitSet(leds, i);
    updateShiftRegister();
    delay(500);
  }
}
 
void updateShiftRegister()
{
   digitalWrite(latchPin, LOW);
   shiftOut(dataPin, clockPin, LSBFIRST, leds);
   digitalWrite(latchPin, HIGH);
}

So would anyone know what else to add to it so the the other 8 led on the second shift reg. Will light up right after the first one than cut out all at once?

The most obvious thing to change is the upper limit on the for loop.

The second is to understand what the bitSet() macro (it is not a function) is doing, and learning how to do that without using that macro. It is NOT at all hard.

Did you give up on your other rhread ?

Have a look at https://www.arduino.cc/en/Tutorial/ShiftOut