RAH, I am aware of the long dormancy but have never heard of a second seed. I also have not researched their lifecycle, yet.
Pat- They are a broadleaf plant that can grow 4ft tall and produce dozens of grape size burrs. Some people will shred their field and a low growing plant will thrive. Some are just naturally smaller yet produce significant burrs. I've seen hogs covered in them dropping them under deer feeders and anywhere else they roam.
