Here's what I did. First I punched a heart on a piece of cardstock. Next I used my pencil to mark out where to punch the next heart. If you look carefully on the left side of this photo you will see a little dot made with a pencil.
Next I put my punch up to the paper and looked for the little mark I had made. You can see it in the photo below. Look on the right side of the heart (in the punch itself). There's a little line made with a pencil.
Punch as many hearts as you would like. Now for the tricky part. First you need to cut your cardstock down to a 1" strip. Then you turn it upside down to punch the other side. What I did was draw little pencil lines where the centre between the already punched hearts was.
Next I lined these up with the bottom V of the heart as in the photo below.
And Voila, a perfect double row of heart punches. There is no measuring in this technique except for the 1" strip. I hate measuring in case you didn't know.
Next I erased all the little pencil lines and taped extra cardstock to the outside edges of the hearts. You can see the tape and the Kiwi Kiss carstock I used in the photo below.
Next tape your piece very carefully to your cardstock (pink in this photo) so that it doesn't wiggle around. Next sponge over all openings in your stencil. Try to make all the hearts look like they have an equal amount of colour.