Louis XIV 4 Sols 2 Deniers - overstruck?

Hello,
I think my coin is https://en.numista.com/catalogue/pieces7760.html but the date is off and the legend seems to be a little...crowded. I see a “7” on the obverse where the date should be, but it’s upside down. There seems to be a fragment of a fleur de lis on the king’s bust as well. Can anyone tell me what’s going on here? Was it overstruck, and on which coin if so?

That is what they call in French "réformé"
The royal coins were regularily overstruck in older coins.

I see, and I think the original coin here is https://en.numista.com/catalogue/pieces7555.html (the upside-down date 1765, fleur de lis and the letter R seem to match, not to mention the size), but was it common to not put the year on such overstruck coin? The rim looks intact except for a few places and yet the date is nowhere to be seen. Or is it just an error?

It was common that the legend of the overstriking coin did not show up completely.
On your coin it is unfortunately the part with the year that is missing.