My Friend Had Sex With Two Different Guys While Ovulating.

My friend had sex with two different guys while ovulating. According to her due date which is April 12th her time of conception was close to July 26th if not before. The 1st guy was when ovulation was first beginning, the second was when it was suppose to be ending which was a week after. Who would most likely be the father? Also too could a girl lie to a guy about how far along she really is?