is it legal for a company to pay new employees more money an hour than a person that has been working for that company for years

Absent a contract which says otherwise, or discrimination for some reason prohibited by statute (age, race, gender, religon,etc.), an employer is not required to pay each of its employees the same, or to pay more to more experienced employees.  Not sure if you follow baseball, but Andrew Miller makes a lot more than Chris Capuano even though they play the same position for the same employer and Capuano (until he was recently cut) was both more experienced and had been with the team longer.