If so then the rest of our coins should be changed 5 pennies, 10 pennies, 25 pennies and 50 pennies to avoid confusion....
No. A penny is a British coin that goes back over a thousand years. A cent, as the name implies, is 1/100th of a dollar. The British penny is now worth 1/100th of a pound, but that has only been in place since 1971. A cent and a penny are not the same thing. The U.S. coin was originally patterned after the large British copper piece, but it was part of the U.S. system, not the British.
In the world of coinage, a penny and a cent are two different things, representing different monetary systems and different values.