There's not really a way to tell right now. The dates are to close together. You will have to wait till the baby is born and get a DNA test.
Iv heard that They have reverse due date calculators for this online.
Due date calculators will tell you about the time that you conceived but it it's not completely accurate because it relys on the fact that all women ovulate at the same time in their cycle which isn't always true and it won't help if you had sex with both on consecutive nights because sperm can live up to 48 hours before reaching an egg. So, you may have had sex with guy 1 on one night and then guy 2 on the second night and got pregnant on day three, but it could be either guy. You need a DNA test to be sure.