Wonder Woman '77 - Who Is Wonder Woman

2nd of 2 adventures told in issue #1 of Wonder Woman '77 Special. Also released as issues #4-#6 in the Wonder Woman '77 series.
Each of the three issues were individually named:
#1 Who's Sleepin in My Bed?
#2 My Own Worst Enemy
#3 Psycho Therapy
Waking up one morning, Diana Prince is stunned to find a blond woman as taken her place as both Wonder Woman and Agent Prince. Even Steve Trevor, her mother, and her younger sister are different.