NVDA accessibility double-speaks "list" on opening dropdown window

[jlangr]

Under windows, with the NVDA app (free download) running, using your page with examples (e.g. "BASIC"):

• After typing the letter c
• Once the dropdown window appears
• When either clicking arrow-down or hovering the mouse below, NVDA speaks "list" twice, i.e. "list list."

[laurentmmeyer]

I can confirm the issue.

I think this happens because of the groupings

Here is the list I have:

And here is the DOM

So there is no surprise that NVDA reads "list" twice but the firstrole=listbox should probably not be there. Does anyone have an idea?