What is a double cut — and why would I use one?
A double cut is when you lay one piece of material over the other piece of material and cut through both pieces at the same time. When properly done double cuts all you to match up two pieces of material when you do not have a usable factory edge.
It is important to  mention that double cuts are considered a ‘professional’ skill and are not recommended by all manufactures for DIY applications.
In the photo above, and only for illustrating the point, we placed one ribbed mat over the other. We then made as poor of a cut as we could. The two mats still fit together and with a little seam tape the joint would hardly be noticeable.
Double cuts are idea when you have seams running both directions and are especially helpful for seams that run from left to right. They also come in very handy when you are having to fit one last piece of material in and do not have a factory edge.
Double cuts are not suggested for piecing together a floor from multiple smaller pieces. Although seams are necessary, they should be minimized.