Opinions please!

I have a friend who is pregnant. She slept with 2 men a couple weeks apart and isn’t exactly sure who the father most likely is. We’ll call them guy a and guy b. She slept with guy a somewhere around august 5 and guy b on august 25. Her last regular period was July 28-august 3 and she went on to have light bleeding august 13-16. She tested on September 13 and it was positive. She then got a test to see how far she was and it showed 6+ weeks. She had her doctor’s appointment today and they also told her she was around 6 weeks with conception being the end of august. Does this mean that guy b is the most likely father since pregnancy is measured from the first day of your last period? Or would guy a be the more likely father since she tested to be 6+ weeks only 2 weeks after sleeping with guy b? Please give your thoughts!

EDIT

No decisions will be made solely based on the advice/opinions given in this thread. I promise you, this is strictly for extra opinions and will not be a deciding factor in anything 😅

She knows there is a need for a paternity test. I left out a lot of information to protect her privacy, which is also why I posted anonymously. I posted here because I know most of you in this community know how pregnancy works from the very beginning better than I do and all I’m trying to do is give my friend some sort of support.