Lmp was 3/29/15. i had sex with two men on 4/16/15. could i have conceived on the 16 even though it says i conceived on the 12th? due date 1/3/16

Test isn't that: accurate to the actual day... it has at least a 15% variability on that. Mainly it locates the particular cycle in which fertilization occurred NOT when in that cycle.

Yes: you are fertile + or _ five days around ovulation. Either one could be the father, or anyone else you had sex with within that 10 day window. Ovulation date varies with cycle length.

Yes.: This is very possible, not knowing your cycle length and regularity I can't tell you acutately when your fertile window likely was, but you definitely could have conceived on the 16 and not the 12. If you can get an early ultrasound and can get a good crown rump length you will have a more accurate idea of how old the fetus is and that may narrow it down, but 4 days is a pretty small difference.