both of the above are correct.. you can even use more than 2 strips on the one side.. as long as the strips (top and bottom) are of equal width.
They have to make the whole come out square to work.. I made some with 2 (two) 1.5" strips and then the top strip was 2.5" and came up with smaller squares that make beautiful coasters.
One way to insure is to piece together your strips for the "striped" side of the square, then measure the width, after you press them.. cut "solid" strip that width, then stitch the two together.. and cut away.