I print my cards double sided but I only use one side at a time. So, if I run out of space on my @home card, I just flip it over to use the back for the same context. I also print my monthly calendar cards front to back because it makes it handy for flipping. It may seem obvious, but I use both sides of my capture cards in the interest of economy and environmental friendliness. So, yah, both sides, but only one side of a card at a time for projects, contexts, and anything else that I need to have a wider view of.