Answer:
Hadassah is her Jewish name, she was re-named Esther, while her previous generation was taken, into captivity. Just like In Babylon, Daniel, he was re-named Belteshazzar. Daniel & three Jews, after being taken to Babylon, were given Babylonian names, also. Hananaih was re-named Shadrach, Mishael was re-named
Meshach & Azariah was re-named Abednego.