Vyvanse twice a day?

I take 30mg of vyvanse every day around 8 am. I get a bit of an energy boost around 9, then after that I get a smooth focus that lasts until 2 pm. After that I'm completely done and I'm being a tired, chaotic, hungry mess. My psych wanted me to try another vyvanse (also 30mg) around lunch, as dex doesn't work great for me. However, I get a bit anxious by the idea of taking 2 times a long acting medication. I wonder how common this is, does anyone else have any experience with this?