Same test, different results

Any reason why two exact same pregnancy tests taken the same day would give off different results? I know it’s still kinda early, but I’m 11dpo & I took two of the 88 cent Walmart pregnancy tests this morning. One at 5AM & the other at 9AM. The one I took at 5AM gave me a VVFL & the one at 9AM gave me a BFN 🤔 why would that happen?