A lot of women overeat during pregnancy. I know I did. It was like my first chance to not worry about weight!! I was very strict and actually a bit obsessive about food prior to being pregnancy so I kind of sort of went crazy. :>) I paid for it in poundage. It came right off after the first pregnancy but then I got pregnant again within 6 months. So, the second time around I didn't gain quite as much weight. I tried to watch it a bit more and that's a good thing because weight was slower to come off the second time around. You really don't need that many more calories when pregnant and if you eat healthy, well balanced diet and make your calories count, you'll be able to control your weight. good luck
You never know if subsequent pregnancies are alike or not. There's no way of telling. each pregnancy could be different, but there is no rule which says the second pregnancy wont be like the first one.
Excess weight gain can be easily prevented by eating healthy options at all mealtimes, not eating junk food, fried foods, drinking excess sugary drinks . There's no need to "eat for two". Sticking to a healthy diet will ensure you do not put on excess weight unless there are other issues, which your gynecologist will be able to tell you. Eliminating excess oil, sweets and refined flour etc. will help.