From the due date of November 17 given to you by a 7 week 0 day ultrasound, the second guy has by far the stronger likelihood of being the dad. Because the first guy was as early as the 11th, he would appear (by the ultrasound measurements of the baby) to be ruled out unless his sperm lasted in your body 8 days or more. While sperm can last a while, medical science is not of the opinion that it lasts 8 days and then still has the strength to fertilize an egg.
Your only problem is that although 7th-week ultrasounds are often spot-on for extrapolating the day when the embryo began, this is a secondary use of ultrasounds, and relies on doing figuring and making assumptions from the baby's measurements. Ultrasounds are designed to check out the baby, not really to establish the date of conception. The mere fact that the two guys were in your same cycle with no period in between means that to be 100% sure would require a DNA test. DNA tests can be done before the baby comes (at a hefty cost).
That all noted, your medical data support the assumption that the baby is the child of the second guy. Unless you simply can't have the first guy be the dad no matter what even if the chances are super slim that he is, your results say that you can be sure enough about the second guy to wait, and just do the DNA test after the baby is born. (If the parents aren't married, it's always a good idea to do a DNA test when the baby is born even if there is no other man in the picture, to establish legal paternity from the beginning. These tests are also lots less costly after the baby is born.)