...it's absolutely someone else, I mean, we all have seen her feet (and their shape) and her ass and pussy before to be able to spot, that that's not her....
Besides, she never really uses a yoga mat.
Apart from that, nice pic, and I think it would pretty much look like that with Marlin
Unfortunately, the biggest giveaway that it's not Malin is that she'd never take a picture like that. Not even if she were wearing lingerie or a swimsuit.