problem with existence condition in while python. turtle

I'm having trouble solving an exercise in a programming book.

The exercise asks that I create 2 turtles and move them randomly, so that each turtle walks 50 units forward, then turn either to the left or to the right, 90 degrees. Turtles should be "born" in a random place within the enclosed space of the screen. They must walk freely until they 'touch'. When this occurs, the program should stop. I was able to write everything down to this final condition.

My difficulty is at the end of the code, in the caminho_ate_parada function. my idea is that as long as the coordinates (x, y) of alex and tess are different from each other, the program keeps running. If the coordinates (x, y) of alex are equal to the coordinates (x, y) of tess, the program must stop. the odd thing is that sometimes the program for when the two turtles are on the same value of the axis (x), however in different values of the axis (y).

What can I increment in the code to solve this?

As I can not send more than 2 files here, I created a blog just to put the code images

link to my blog with images

import random
import turtle

alex = turtle.Turtle()
tess = turtle.Turtle()
wn = turtle.Screen()

tess.shape('turtle')
tess.color('blue')
tess.speed(0)
alex.shape('arrow')
alex.color('red')
alex.speed(0)

def isInScreenAlex(w,t1):                                
    leftBound = - w.window_width()//2 + 100              
    rightBound = w.window_width()//2 - 100               
    topBound = w.window_height()//2 - 100                
    bottomBound = -w.window_height()//2 + 100            

    turtleX = t1.xcor()                                  
    turtleY = t1.ycor()                                  
    stillInAlex = True                                   
    if turtleX > rightBound or turtleX < leftBound:      
        stillInAlex = False                              
    if turtleY > topBound or turtleY < bottomBound:      
        stillInAlex = False                              
    return stillInAlex                                   


def isInScreenTess(w,t2):                                
    leftBound = - w.window_width()//2 + 100              
    rightBound = w.window_width()//2 - 100               
    topBound = w.window_height()//2 - 100                
    bottomBound = -w.window_height()//2 + 100            

    turtleX = t2.xcor()                                  
    turtleY = t2.ycor()                                   
    stillInTess = True                                   
    if turtleX > rightBound or turtleX < leftBound:      
        stillInTess = False                              
    if turtleY > topBound or turtleY < bottomBound:      
        stillInTess = False                              
    return stillInTess                                   


def compXa():                                                                              
    MaxXAxisA = int(random.randrange(- wn.window_width()//5, wn.window_width()//5 ))        
    while MaxXAxisA % 50 != 0:                                                              
        MaxXAxisA = MaxXAxisA + 1                                                           
    return MaxXAxisA                                                                        

def compYa():                                                                              
    MaxYAxisA = int(random.randrange(-wn.window_height()//5, wn.window_height()//5 ))       
    while MaxYAxisA % 50 != 0:                                                              
        MaxYAxisA = MaxYAxisA + 1                                                          
    return MaxYAxisA                                                                       

xa = int(compXa())
ya = int(compYa())

alex.penup()                                                                               
alex.goto(xa, ya)                                                                          
alex.pendown()                                                                            


def compXt():
    MaxXAxisT = int(random.randrange(- wn.window_width()//5, wn.window_width()//5))
    while MaxXAxisT % 50 != 0:
        MaxXAxisT = MaxXAxisT + 1
    return MaxXAxisT

def compYt():                                                                             
    MaxYAxisT = int(random.randrange(-wn.window_height()//5, wn.window_height()//5))
    while MaxYAxisT % 50 != 0:
        MaxYAxisT = MaxYAxisT + 1
    return MaxYAxisT

xt = int(compXt())
yt = int(compYt())

tess.penup()                                                                              
tess.goto(xt, yt)                                                           
tess.pendown()                                                                            


def positionAlex():
    if isInScreenAlex(wn, alex) == True:

        coin = random.randrange(0,2)
        if coin == 0:
            alex.left(90)
        else:                                                                            
            alex.right(90)                                                             

        alex.forward(50)

    else:
        alex.left(180)
        alex.forward(50)


def positionTess():
    if isInScreenTess(wn, tess) == True:

        coin2 = random.randrange(0,2)
        if coin2 == 0:
            tess.left(90)
        else:                                                                             
            tess.right(90)                                                                

        tess.forward(50)

    else:
        tess.left(180)
        tess.forward(50)



def caminho_ate_parada():    
    while tess.xcor() != alex.xcor() and tess.ycor() != alex.ycor():                      
        tess.xcor()                                                                       
        tess.ycor()
        alex.xcor()                         
        alex.ycor()                                                                       
        positionAlex()
        positionTess()


caminho_ate_parada()
wn.exitonclick()