I double strapped mine as well. Took me about 30 minutes, but its much more solid than any of the other ones I've seen people wear.
1. Cut the empire strap off the pivots.
2. Insert your first KM strap
3. Take a sharp knife and cut out the threading on the 2nd strap's butterfly,
4. Insert using needle nose pliers
5. re stitch butterfly on second strap with needle and thread.
You can't really see it, but its in there.