As someone who has done a bit of goalkeeping coaching in my time I can confirm that there is NOTHING suggesting that left footers or right footers are more likely to score penalties.
As a keeper you have to know which foot they're using of course, but you can tell this from the run up.
A shit penalty taker, whichever foot they use, will tell a keeper which side the ball is going by the engle of their hips just before they strike the ball.
Shit takers also favour directing their penalties in the direction of their favoured foot (eg a right footer will favour hitting it to their right).
A good penalty taker will be happy either side and will disguise their hip angle to confuse the keeper.
Oh, and shit keepers also have a favoured side to dive. But it's not based on whether they are right or left footed.
