Haa, OPK yang tunjuk 2 line memang boleh berlaku beberapa hari because the LH surge (hormone yang OPK detect) boleh naik turun, bukan just sekejap je, so kadang 2 line, kadang terang, kadang blur. True, ovulation itself happens within 24-48 hours after the LH surge peaks, tapi the surge itself boleh drag across a few days la. A few of us mums trying for baby noted the same thing, some of us got 2-3 days of positive tests. Kalau worry, best to check with your doctor or fertility specialist sebab timing boleh vary dari person to person, especially if ada any hormonal stuff going on.