Have you seen this article in Knitty? In this absolutely fascinating article, Kory Stamper writes about literally knitting 2 socks in 1. Using the idea of Double Knitting, she explains that you can knit one sock INSIDE of another. Now, that's taking my pleasure of knitting two socks at the same time on a Magic Loop to a whole new level!
I've been wanting to give Kory's socks a try but it wasn't until this week that the knitting cosmos shifted and everything came together in a perfect fit!

First, I reviewed Kristin Nicholas' book - Kristen Knits.
Among her collection of wildly colorful projects, I realized that her Colorful Socks were made for Kory's 2 at Once method.
I struggled with Kory's cast-on instructions. I suspect it is because I'm not very good at thinking spatially. After an hour and a half, I finally got it!
I thought it might help if I shared my own photos and instructions for the double knit cast on of two socks simultaneously.
Kory says that the cast on is the most confusing part of the entire pattern. Well, if that's the case, I'm glad I've got it figured out!
Start with a slip knot of each color of yarn.
The next step is very important for you to understand to "get" this unique cast-on method. Twist the top strand so that the bottom of the stitch is on the left side of the needle. From now on, you need to think of these two sides, or edges, of the needle as two seperate "areas."
See how I hold these stitches?
You are now going to use a cable cast-on to alternate adding one stitch to the "brown" side and one stitch on the "purple" side.

Start with the "brown" side by putting your right hand needle tip through the brown loop like a usual cable cast-on.
Pull the yarn through and place the new loop onto your left hand needle.
Now you have the bottom of two "brown" stitches on the right side of your needle and one "purple" stitch on the left. Time to make a second "purple" stitch.
Twist, or spin, your group of stitches around the needle so that the "purple" stitch is on the right and the two "brown" stitches are on the left. The way to think about this for the rest of your casting on is that whichever group of stitches need to have a new stitch added, must be on the right side of your needle.
Your are going to repeat the cable cast-on maneuver with the "purple" yarn to make a second stitch. Then twist, or spin, the group and add a third "brown" stitch. Then, twist, or spin, and add a third "purple" stitch.
See how it works!! Two completely seperate sets of cast on stitches ready to be joined and knit as two completely seperate sock legs. Now I'm ready to continue on with my "socks" this weekend.