Who’s the baby’s father?

So my sister is pregnant and unsure of the father. The picture I underlined the days she had sex, the couple days in a row is guy #1 and the 8th is guy #2. She told both guys she’s pregnant but didn’t tell either one that there’s a chance it’s someone else’s baby.

She got a positive test on February 18th, here’s the test

she went to the doctor and Gestational age is 5 weeks 5 days but there’s no pole . Is it possible it can be guy #2s baby even tho it was only 10 days after sex??, her period was supposed to start february 11-13th. Any advice would be greatly appreciated!