Anyway, in neck shaping with 104 stitches, the pattern says to "work 36 sts, join 2nd ball of yarn and bind off center 32 sts, work to end. Working both sides at once, purl 1 row"
Just do what it says ..... work 36 stitches and add a new ball of yarn WHICH will be the yarn you use to do the bind off which will end up putting that working yarn on one shoulder and the first ball of yarn on the other shoulder because you can't jump the bind off after you've bound it off. So it says to bind off and then finish that row in pattern after the bind off .... NOW purl that section and then with first ball of yarn not second ball purl that other side. They just want you to MAKE sure you do the same thing on both sides of the bind off .