Scarf Q - slip stitch

I was thinking about trying to do a stripy knitting scarf but the yarns I picked out half are light worsted and the others are heavy dk.
do you think if I double the dk I can do it that way - worsted on one side and dk on the other, sewn or knit together?
I can’t find any other yarns that are the right colors…
maybe I am kidding myself I could even do it if it was possible, but I would just like to know if theoretically it could happen even if it won’t for me.

also, does anyone know if slip stitch patterns use more yarn than normal knit-purl ones? or depends on the slip stitch? (I am using the simple vertical stripes if it does.)

thanks!
rebecca

I’m not sure of the answer, but I’ll bump this up for someone who might know.