u mean 74HC595 ?
two leds is not a problem, you won't be needing the resistor, remember there's only ever 1 pin lit up at a time, so you could probably stack 10 LEDs on 1 pin x 8 pins (80) because there's only ever 10 LED's on at one time, going through pins in a cycle that's too fast for the human eye to discern.
What do you mean by one at a time?.. 74HC595 has latch ...latch clock is different than serial input clock. I can load the register and then command output for all of them.
My parallel scheme was something like this
-----LED-------
| |
VCC --- | |-----RES---- 74HC595
| |
-----LED-------Since one LED need 10mA the current flowing through 74HC595 will be 20mA.
I set all latch bits to 0V and all leds light up at a time
There's never any more than 1 pin on at a time, so the total amps used is only the sum of 1 pin, of course you control all 8 of them, it's an 8-bit serial in serial or parallel out shift register.
And you don't need the resistor if your using more than one LED, the resistors only there to stop the LED from frying out, with two LED's it's enough to not need the resistor.
-----LED-------
| |
GND --- | |------------ 74HC595
| |
-----LED-------
I've got 3 595's driving 24 LED's and 5 relays piggy-backed on top of 5 of the LED's, the LEDs over the relays don't need resistors, and I'm using those evil MCD 10000 high-bright green LED's, they shine as bright with 1 595 and 8 LEDs, or 3 of them and 24 LEDs plus the relays.