Mozilla-bug:

Multiple-select:

Single-select:

Select first field (default). Reload the page and "Number 1 again" will be selected as well.
Or go to other page - and then go "back"

Variant: Select "Number 2" and reload.

If you want to restart this test, don't reload the page (which is the problem), but type in the URL - or go to this page again via a link like this. In this case Mozilla won't try to rebuild the state of the form.

This page is 100% static HTML and can be copied.