I'd just go get a pregnancy test at the drugstore, one for her and one for you or just one for you, and take it with first-morning urine. What were you two doing, goofing off in the bathroom and pouring urine samples over the stall walls?
that is really odd haha , well just calm down and ask your doc asap !
How did they get mixed? I would definitely ask for a retest before either of you tell your significant others anything.