การสร้างวัตถุเต่าหลายครั้งใน Python

import turtle
t = turtle.Turtle()
t.speed(0)
t.dot()
t.goto(100, 100)
turtle.done()
import turtle

# FIRST DRAWING: 
t = turtle.Turtle()
t.speed(0)
t.dot()
t.goto(100, 100)
turtle.done()

# SECOND DRAWING: 
t = turtle.Turtle()        # ERROR OCCURS HERE WHEN FIRST WINDOW IS CLOSED.
t.speed(0)
t.dot()
t.goto(-100, -100)
turtle.done()