Help!?

Meagan
I used a Clearblue Advanced Digital OPK 1 week ago (when Glow estimated ovulation) and got the "Peak Fertility Smiley." I tested four days afterward and got negative/low fertility. I tested again yesterday (6dpo) and today (7dpo) and got the "High Fertility Smiley." Is it possible that I ovulate more than once per cycle? Has anyone else experienced this?