What bunny girl said. But you can also ovulate twice, although its extremely rare. It happened to me with this pregnancy but only one egg was fertilized apparently. I had been using OPKs & temping, both showed I ovulated twice a week apart from eachother which is even more rare since if it happens its within like a 24-48 hour time frame. Then at my first ultrasound my doctor said I had 2 corpus luteum cysts on left ovary & said it was because I ovulated twice.