Can I Take Levenolle Twice In One Cycle?

I took Levenolle One step on 17th April, and had a period shortly afterwards. Unfortunately, the method of contraception we were using failed again last night and I am unsure as to whether I can take Levenolle again, as all of the advice I have read says it should not be taken twice in one cycle. Why is this advice given? Are there negative side effects now, or for the future? Thank you.
I am 24, and take no other medication. Fit and healthy.