Basic OPK or digitals - help

Hello i am really hoping someone can help ....

i have always used the basic opk the cheapie strips and always found myself to have the surge around day 13/day14.

TTC 2 years + and decided to splurge in the Clearblue Digital test the one where it give you a circle ( no lh surge ) or a smiley face (lh surge - expected to ovulated in 48 hours ) please note this is NOT the flashing one which i believe is the advanced kit.

Anyway with the Clearblue digital i am getting the Smiley Face around day 9...so considerably early than what the cheapies detected.

Has anyone else experienced this?