I would like to duplicate the default product layout grid in a Commerce Kickstart2 site
It's because the CSS for the list elements is not being applied

display: inline;
float: left;
min-height: 380px;
height: auto;
margin: 0;
padding-right: 5px;
padding-bottom: 30px;
width: 230px;


So you need to change the CSS selector so that it does apply.

I think that isn't the right answer though, instead of duplicating the template I think you should edit the view so that it shows your brand pages with the brand info at the top rather than put it in the template (if that is what you're doing).  It'll take a while to work out but the site will be much easier to maintain over time.