Como colocar uma verificação de entrada para uma calculadora em python?

print("Welcome to the Kinetic Energy and Gravitational Potential Energy Calculator")
print("Which Calculator would you like to access?")

Choice = str(input("Type in KE for Kinetic Energy and GPE for Gravitational Potential Energy:"))

while Choice != "KE" or "GPE":
    print("Error. You have not entered a valid choice. Please type KE or GPE.")
    Choice = str(input("Type in KE for Kinetic Energy and GPE for Gravitational Potential Energy:"))


while Choice == "KE":
    print("You have chosen the Kinetic Energy Calculator.")
    mass = float(input("Type in the mass of the object in kilograms (kg):"))
    velocity = float(input("Type in the velocity of the object in metres per second (m/s):"))
    result = 0.5*mass*(velocity**2)
    print("The KE is:", result, "J(Joules)")
    Choice = str(input("Type in KE for Kinetic Energy and GPE for Gravitational Potential Energy:"))

while Choice == "GPE":
    print("You have chosen the Gravitational Potential Energy Calculator.")
    mass = float(input("Type in the mass of the object in kilograms (kg):"))
    height = float(input("Type in the height at which the object is in metres (m):"))
    result = 9.81*mass*height
    print("The GPE is:", result, "J(Joules)")
    Choice = str(input("Type in KE for Kinetic Energy and GPE for Gravitational Potential Energy:"))

Eu tentei usar "ou" para que a verificação possa incluir 'KE' e 'GPE', mas quando você executa o programa, mesmo se eu inserir KE ou GPE, o primeiro loop while continua! Como posso fazer funcionar?