How do you know? The font number does not matter as the website wont see that. To check uniqueness of the fonts you would need to actually compare the content of installed font, not only the name. It would be totally possible that the installer is packed with the font, but dynamically alters it before actually installing it.
The version number is part of the font name (e.g. “TeamViewer15”). Websites can apply a list of known font names to an element and see which are available based on whether a test element changes size after applying the font.