Two different results

I have been testing for ovulation all week, since CD 15. I don’t normally get a high until CD 19-22, but I had been getting highs since CD 17, so today (CD 19) I tried two separate test and the old tester that I bought last month that has been giving me highs all week gave me another high, but the new tester that I just unpackaged today gave me a negative. Which should I trust?