YOU CAN GET FALSE NEGATIVES BUT YOU DONT GET FALSE POSITIVES.
The postive one is the one you should go with. The negative one may have come out that way because that test isn't has sensitive, or because it wasn't done with morning pee. There are a lot of factors. But hardly ever will you get a false positive though false negatives happen all the time.
I was always told positive means positive no matter what...so I would say yes...check the expo date too... Or go get a blood test to make sure