What's the problem this feature will solve?

Make unambigious what the values of the parameters used from parametrize are.

Describe the solution you'd like

When duplicated values are used in parametrize, pytest adds a number after each duplicated value, starting from 0 and this confuses what the actual value of parameter is.

Example:

@pytest.mark.parametrize("a", [1, 2, 10, 11, 2, 1, 12, 11]
def test_params(a):
    print('a:', a)
    assert a > 0

This result in following output from pytest:

test_a_1.py::test_params[10] PASSED                    [ 12%]
test_a_1.py::test_params[20] PASSED                    [ 25%]
test_a_1.py::test_params[10] PASSED                    [ 25%]
test_a_1.py::test_params[110] PASSED                   [ 37%]
test_a_1.py::test_params[21] PASSED                    [ 50%]
test_a_1.py::test_params[11] PASSED                    [ 62%]
test_a_1.py::test_params[12] PASSED                    [ 75%]
test_a_1.py::test_params[111] PASSED                   [ 87%]

It is clear that a has the value 1 the very first time and not 10, so confusing with the real 10 later.
Pytest adds a sequential nbr immediately after each duplicated value and that is very confusing

Alternative Solutions

Do not do this and leave the values as they are, so I would like following output:

1, 2, 10, 11, 2, 1, 12, 11 as in parametrize list