Duplicate stitch is a type of embroidery stitch, to add colors after you’ve finished knitting. Duplicate stitch covers a knit stitch, and works best on stockinette. It is practical when adding small details with colored yarns, and can be used to fix minor mistakes. For example, the diagonal lines of an argyle pattern work great in duplicate stitch, otherwise you would have to work one narrow (usually one stitch) line of stitches as you are knitting. Duplicate stitch should not be used for large areas of color because the fabric will become too thick. Here’s how to do it:
Simply bring up a threaded tapestry needle below the knit stitch to be worked, leaving a 6 inch tail on the wrong side of the work to be woven in later. Insert the needle under both loops from right to left of the “V” one row above and pull the yarn through. Insert the needle back through the first hole you came up, then bring needle up at the base of the next stitch to duplicate. Continue in this manner.
It is really that easy!