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 =)