Remove element if next element is the same from list in Python

Question

I have the following list list1 = [1, 2, 3, 3, 4, 3, 5, 5]. I want to remove duplicates from the list only when the duplicate is after its original element. So in this case the output would be: [1, 2, 3, 4, 3, 5]

I tried the following simple implementation:

for x in list1[:-1]:
    NextIndex = list1.index(x)+1
    if list1[NextIndex] != x:
        O.append(x)

But of course it won't work because i'm doing if list1[NextIndex] != x. I can't even use list1.remove(), since removing from lists while looping doesn't work. Is there any way to do that with list comprehension maybe?