Duplicate test nodeids in command line arguments show incorrect collection count but execute only once

Description:

When passing duplicate test nodeids in the command line arguments, pytest shows an incorrect collection count but only executes the test once.

Steps to Reproduce:

Run pytest with duplicate test nodeids:

pytest tests/test_foo.py::test_pass tests/test_foo.py::test_pass

Observed Behavior:

collected 2 items

tests/test_foo.py::test_pass PASSED                                      [100%]

============================== 1 passed in 0.01s ===============================

The output shows "collected 2 items" but only executes and reports 1 test

The progress percentage shows [100%] after one test

Expected Behavior:

Either:

Pytest should deduplicate the nodeids during collection and show "collected 1 item", or

Pytest should execute the test twice (if intentional duplicate execution is desired)

Environment:

pytest version: 8.3.5

Python version: 3.12

OS: macos

Additional Information:

This might cause confusion when:

Accidentally passing duplicate tests in complex command line invocations

Using tools that generate pytest command lines automatically

Trying to understand test counts in CI output

Start by reproducing the command with the duplicate tests/test_foo.py::test_pass nodeid and trace how command-line nodeids are collected and reported. Done means the collection count, progress percentage, and executed test count consistently reflect the chosen duplicate-nodeid behavior, with coverage for this reproduction.