2 spikes in BBT

Hi. I'm new to glow but have been tracking my cycles on other apps before now. I don't usually get another spike in temp after ovulating. (I know the first spike was ovulation as I'm using the clearblue opk advance). Do any of you know why this has happened? I test same time each morning and am usually consistent as you can see from previous 3 days. Confused and would appreciate your thoughts xx