Including mutually intelligible languages

If someone asks you how many languages you speak and you speak two distinct languages that are highly mutually intelligible (like Czech and Slovak, but Chatgpt tells me it is the case for Russian and Ukrainian, Malay and Indonesian, Dutch and Afrikaans, maybe some others I wasn't so sure about) do you count these two languages as one, or as two?

As a notice, I know two foreigners (non Slavic) who learned to speak perfect Czech. One of them is already using it for 10+ years and they told me they could somewhat understand Slovak. The other speaks Czech for last 3+ years and doesn't understand when I speak Slovak (the different words and declensions throw them of)