Clear Blue Advanced OPK Peak for 4 days...any insight?/Similar experiences?

Co

So, I've been testing with clear blue advanced digital ovulation test since 8/2, got 2 days circle "low fertility", had flashing smiley "high fertility" from 8/4-8/6, got a solid smiley "peak fertility" 8/7 AM. Of course the solid smiley lasts for 48 hours. So I thought for sure I was ovulating soon and started BDing like crazy.

However, I have also been doing cheap OPK strips and was doing them once a day in the afternoon and had not yet had a positive so I increased my testing to 3x daily after my solid smiley. As of yesterday I still hadn't gotten a positive so this morning when my clearblue finally went blank I used it again and again got a solid smiley. Finally got positive OPK stick this evening (pictures below)...why did clearblue tell me so soon?! I might have missed my real peak if I hadn't been using cheap OPKs!! Gah!

Anyone ever had this happen? So glad I'm using the cheapies too! Last month they matched up 1st solid smiley with 1st + strip which made me so confident but now I'm not so sure!