Python : How to use random sample when we don't need duplicates random sample

My Code

import random

MyList = [[1,2,3,4,5,6,7,8],[a,s,d,f,g,h,h],[q,w,e,r,t,y]]
MyListRandom = []
random_number = 5
i=0
while True:
     random_list = randint(0,len(MyList))
     element_random = random.sample(MyList[random_list], 1)
     if element_random[0] not in MyListRandom:
     i = i+1
     MyListRandom.append(element_random[0])
else:
    continue 
if(i>=random_number):
    break

if I don't want to use this code to check it

 if element_random[0] not in MyListRandom:
     MyListRandom.append(element_random[0])

Is there a better way more than this if i don't want a duplicates sample?