The due and delivery dates indeed point to Guy #2 on July 27th. That is 14 days after your last period began, the probable ovulation date when your sex drive would have been highest. Finally, the fact that you had a normal full blown period after the June 30th incident eliminates Guy #1 from contention.
For an estimated due date of April 19, the computed conception date is July 27. You can put the estimated due date of April 19 into a conception calculator if you want to check this. That is why I was asking what your reason to worry was. Did you not want the July 27 guy to be the dad?
Did you get the due date from an ultrasound in the early weeks of the pregnancy? Did you have the baby when expected?