Lines darker on Walmart tests than dollar tree?

Alisha

Tried to google this but came up with nothing. I took a Walmart equate test and it was positive. Took another one the next day and it was darker. Ran out of Walmart tests so I had to use a dollar tree test. Still positive but a lighter line than the Walmart tests!

Does anyone know if line darknesses vary by brand? Or maybe I’m having a chemical.

Any insight?