Need to program ATmega for duplicate outputs on 2 different pins

Using Arduino Programming Questions
3
  1. you can simply hard-wire them; simplest and most effective solution;
  2. you can rewrite the pwm driver so in the isr you flip both pins; requires some work on your part;
  3. you can put an interrupt on the master pin, trigger by its state changes. in the isr, you flip your slave pin(s); requires the most amount of work but it is fully transparent: once set-up, no user intervention is required.