From Reversible Two Color Knitting by Jane Neighbors This stitch has a slide after the cast-on that I am interpreting to mean that row 1 is WS for this version. Row 1 in light, row 2 in dark, row 3 in light, row 4 in dark This is the same as double garter except that the color is changed every row.
Shown with a cast-on count of 2 stitches.