Go buy clearblue digital with weeks estimator. It's easy to read because it will say "pregnant" or "not pregnant"
An evaporation line is a faint line where the test line is at. They get darker on the test after a few hrs but some tests show the evap line even before use and then the urine makes it darker. You can google images evap lines and see what comes up and compare.
Whats an evaporation line
^ not true. Blue dye tests give false positives a lot lots of tests have a too-dark evaporation line that shows prior to tesring if you look and then becomes emphasized with the urine,, and if you have a chemical pregnancy you could get a false positive too. Not impossible.
Test again in a couple days. Or get a blood draw from the DR. It is impossible to get a false positive.
Are you sure the first wasnt an evap line? A lot of tests if you look close you can see the evap line