Duo by Kristi Porter

Duo

Knitting
March 2003
Worsted (9 wpi) ?
16 stitches and 32 rows = 4 inches
in garter stitch
US 7 - 4.5 mm
400 - 828 yards (366 - 757 m)
English
This pattern is available for free.

Description from Knitty.com:

Here are two versions of a fun little sweater just right for spring.

Both styles feature wide ribbing and a lapped boat neck that buttons at the shoulders. They’ve got a bit of style, but are definitely ready for everyday wear, particularly when knit with an easy-care yarn.

Feel free to mix and match elements from both sweaters to design one perfect for your little one -- stripes, sleeve length and body length can be used interchangeably across patterns.

This is also a great pattern for sibling sweaters: good for girls or boys with lots of room for variation.

Note that the gauge in a cotton yarn such as Cotton-Ease expands after wearing, so the fit will be a little looser.