Double knitting two colours at once - Tough as heck?

This technique is another one I'd never heard of, but a pattern demanded it. "Double Knitting" usually means working two strands of yarn at the same time, alternating Knit / Purl stitches so that you build up a different colour on each site. 

"Easy peasy!" I thought, so I had a go - and the weird 'melted ice cream sandwich' of yarn to the left is the result. Knitting pink and purple yarns together (apologies for the horrid photo, my phone is dreadful!) in alternating stitches gives you something like this. 

I had to dig around a bit to find a tutorial that worked for me as most seemed to skip over the fact that quite often you get a nasty ragged edge on your work as you progress, not very good if you're trying to knit something with an even edge like a scarf or something fancier. 

This one over at Nimble Needles is the best I've found, as it lays things out nicely and includes a video tutorial if you need to see the technique in action. As the article suggests, there isn't just one single solution to double knitting, there are several methods and some are more complicated than others, but this one worked for me. The best thing about double knitting is that DK yarn finally 'makes sense' (anyone who has tried knitting with DK probably curses how fiddly and fine DK weight yarn is) and the resulting fabric is a nice thick and cosy weight, perfect for jumpers and scarves (it also doesn't curl as much as standard knitted / purled stitches do).