Split workouts

I have been using this site for a little over a month now and am really enjoying watching what I'm doing. I'm pretty meticulous about everything I eat and workouts. For my job I have tried to stay in shape, for the most part been successful. Since beginning, I started out on the elliptical for about 33 minutes doing the weight lose program. Now after a month and a half I am doing various preprogrammed sessions on the elliptical but have increased from the 33 minutes to a full 60 minutes with a 5 minute cool down. At the end, I'm semi tired and don't feel like I have done enough. So after a few minute rest, I'm back at it for at least 20 minutes and as long as another 60 minutes.

So here is my question. Am I doing to much cardio all at once or would it be better off splitting up my cardio sessions? I have the convenience of having a small gym at work, so I could do a hour in the morning and a hour after work. I'm trying to lose another 30 lbs before softball, while building my stamina as well.

One additional question, after a 65 minute workout, the elliptical says that I burned over 900 calories... Is that really possible? Any suggestions would be appreciated.