But the pattern is to CDD every other row! When you repeat row 3 you're putting in another decrease
CO 49 stitches, marking center stitch with safety pin
row 2 (ws) knit
row 3 (rs) knit to 1st stitch before center stitch cdd, knit to end
row 4 knit
row 5 with first color indicated repeat row 3 (that is, do a CDD)
row 6 with first color indicated repeat row 4
Repeat rows 3-6 until 3 stitches remain.
OK, now it makes sense. The remaining squares should work correctly in pattern with this first square.