Ovulation vs. Pregnancy test

I took an ovulation test by accident a couple days ago instead of a pregnancy test and it came back positive when I already ovulated once this cycle. I read that these tests can also pick up hcg and got really excited, but I've taken two pregnancy tests and they came back negative. My period is due in a couple of days, so it's weird that I'd get a pos lh test so late in my cycle. Any thoughts?