Ad 1 47 clicks at $0.26 per click Ad 2 13 clicks at $0.15 per click Any idea why this could be happening? Thank you!
First off, Facebook's algorithm is auction-based, so there's no literal way to tell why something costs less than something else, even though they're completely identical, which is not your case.
In your case, If your CTR is higher on one of the images, that shows facebook that your audience is engaging so they're rewarding you by giving you a smaller cost per click. So that's why.