Every knitter knows what this is, creating a two-sided fabric using two balls of yarn. A baby blanket pattern by Eleanor Roosevelt uses this technique. But there is also another use for it. Creating two identical items using one set of needles.
Case in point-socks. Knitty has an article on the technique and how to do it using double pointed needles (which is the only way you could knit a pair of socks with them). I've adapted the method to my personal style of knitting, however, I've not finished a pair of socks using the technique. It's so easy to cross the threads and I sometimes don't catch it until I've done several rounds, and then just fixing the one crossed stitch as indicated in the instructions doesn't account for if you continue to use the wrong yarn end on the socks. The only method of fixing crossed threads is to carefully un-knit back to the crossed threads and uncross them, then continue. This is tedious and usually has me putting the project down or simply frogging it and redoing on separate needles.
Okay, to avoid having to un-knit a bunch of rounds in the case of crossed threads, I would recommend that you check every few rounds by pulling the inside sock up and out, then check between them. Crossed yarns are easy to spot. While this will slow you down a bit, it's not much different from checking your pattern every few rounds on more complicated patterns. Still, overall, the process is much slower than doing a pair on circulars.
So, why am I making another post about double knitting? I'm still determined to do a pair of socks to completion. Would I recommend this technique to do a pair of socks regularly? No. Why? Because doing a pair of socks on two circulars or using the magic loop method is tons easier. To alleviate the 'Second Sock Syndrome' I do recommend doing both socks together.
To be able to double knit a pair of socks, the knitter would need to work on them with no distractions (this is not a mindless project to be done while watching tv). The knitter must keep their mind on their work or else they will cross their yarns. To have to remove the heel stitches and put them on separate needles to do the heels is also tedious, and this is where using two circulars or magic loop and keeping the socks separate is the superior method. Because once you get your heels knitted (and I recommend short row heels for this), you then must arrange them all back on one needle to continue in the round (tedious again)
Then there's the matter of the toes. Again, you have to divide out your stitches and put them onto separate needles (in my opinion) and finish them individually, as you did the heels.
So why am I doing this? Like most who comment on the technique, just so I could say I did. Once I finish a pair doing this I will likely not do this technique again, unless I'm making double-sided baby blankets, throws or potholders where crossed yarns won't be a problem. It's just a method for those who want to draw attention to themselves by doing it out in public so they can act smug and superior as they explain what they're doing. Personally, I wouldn't act so smug about this technique, you'll more often than not make mistakes that will likely be tedious to undo. You'll make fewer mistakes using the other two techniques for knitting a pair of socks at the same time. And the last plus about the other two methods? You can use any pattern you want and make fancy-schmancy socks. double knitting is best done using a basic, no-frills, plain knit sock pattern.
However, your socks will go quicker by doing them on two circulars or using magic loop and keeping them separated the whole time. You'll still have to do the heels individually, but not the toes.
An addendum: While you can get into a rhythm with double-knitting socks, don't be fooled into thinking it's mindless knitting. One little moment of inattention and you have crossed yarns. So, unless you're doing as the article recommends and knitting with two contrasting colors, I wouldn't recommend letting yourself get distracted while doing it.