or does it do the same damage
Parental Bond allows the Pokémon to attack twice each turn on the same target (even if it fainted), with the second attack being half as strong as the first.
http://bulbapedia.bulbagarden.net/wiki/Parental_Bond_(Ability)
The ability Parental Bond uses most physical attack twice but the second attack will be half as powerful as the first.
Source: Experience and several websites.