No it is not unlikely at all.
That is when many women get pregnant, after they come off BC. They do not think that they would be 'fertile' yet, so they take chances.
TWO lines will always be present in an ovulation detection kit, no matter what time of the month it is.
You just have to know how to read it.
http://www.peeonastick.com
This is site that explains how to read ovulation detectors, they have pictures etc.. So you could see the difference =)