How does CSRF validation work in Django and why do 2 different tokens still pass the check?

Question

I'm currently reading up on CSRF and was wondering how is it possible for the CSRF validation in Django to validate 2 tokens as equal even if the values differ?

if not _does_token_match(request_csrf_token, csrf_token):
    reason = self._bad_token_message("incorrect", token_source)
    raise RejectRequest(reason)

This is the token check function, and it consists of:

def _does_token_match(request_csrf_token, csrf_token):
    # Assume both arguments are sanitized -- that is, strings of
    # length CSRF_TOKEN_LENGTH, all CSRF_ALLOWED_CHARS.
    return constant_time_compare(
        _unmask_cipher_token(request_csrf_token),
        _unmask_cipher_token(csrf_token),
    )

I've used the CSRF token that Django automatically generates and returns back in the response, and one which I generated manually with the get_token function from django.middleware.csrf and the result of _does_token_match is True. Not sure that I understand why is that.