My dating scan 1st august 2014 dated me 12w 5days who is the dad? the one on the 20th april or the second on the 29th april til middle of may?

Second one: Thirteen weeks is a trimester, or 91 days, which puts your date if conception around the 3rd of May. Since there is an error factor of +/- 5d - 2weeks, you will probably need to do paternity testing, since within this error factor, either one could be the dad, within the error if the testing technique. Dad #2 is the front runner in this calculation, but can't rule out #1 by dates alone