really confused - please help!!!

Hi ladies - something strange just happened- I am just over 5 weeks pregnant and I'm obsessed with testing due to previous mc. I took a test this morning and it was a bfn (see top test in pic) I panicked, drank loads of water and took another right away and it was a bfp (bottom test in picture) I'm freaking out - is it a dodgy test or what should I do? Has this happened to anyone else?