What is twine knitting or double knitting?
Twined knitting is a technique that uses two yarns alternately in each row. It is a little tricky to learn, but if you are already skilled it isn’t hard. Candace Eisner Strick and Beth Brown Reinsel, among others, have books devoted to learning the technique and the patterns for it. Two Ended Knitting is a book about this by another author whose name escapes me at the moment from Norway.