I've done that before! It was hard to adjust to but if you put the effort in you'll be fine. Get lots of sleep the night before...go to bed a few hours earlier than you usually do! Eat well...try to stick to healthier foods even if it means packing your lunch every day and not buying the school food. Drink lots of water...will help you feel more awake, energized and of course hydrated. Ask your coach for your second team if you can grab a snack or take a short rest/study break while your second team warms up. You'll already be warm from the first team so I think a 15-20 min break will be a good recoup, especially once it gets to the point where you know you'll be doing lots of conditioning and/or full outs on either team. I'm sure your coaches will understand!