2 LH surges in my cycle.... Help!

So I have been taking Femara for the last two cycles. I was told by my OB to start taking ovulation predictors on day 10 of my cycle. I noticed in each cycle I get an LH increase but no actual surge..... The opk lines become darker right after I finish my round of Femara (I take day 7-11) but I never get a positive test during this time. Then after day 12 the lines start getting fainter and then around day 16 they start getting darker again (I usually ovulate on day 17). I'm just wondering if anybody else experiences this phenomenon? I didn't do this on clomid....or even when I wasn't taking meds....