confuse

Hi mommies! nung 2mos kasi yung tyan ko nag pa ultrasound ako and yung edd nya is march 1. then nung 6mos na yung tyan ko nag pa ultrasound ulit ako and yung edd nya naman is Feb 7 na. is it possible po ba na mas mapaaga or mas tama yung unang ultrasound ko? thank you.