Is it Okay to Read Two Books at Once?

Just a quick one today. I'm currently reading two books at the same time (Snow Like Ashes by Sara Raasch and Daughter of Smoke and Bone by Laini Taylor) and I'm wondering what your thoughts are on this. When I was younger, I considered it absolutely ridiculous to read more than one book at a time. It almost felt like I was betraying a book if I didn't give it my complete attention until we reached the end together. I also think I was worried about confusing plots or characters between the books or something. But recently, for whatever reason, I've started doubling up a little. To be honest, I kind of like it because having two books going means I can pick up whichever one I'm in the mood for at the time. What do you guys think? Do you read books one at a time? Or two, or three, or as many as you can cram into your brain at once?