Hi, this is just a guess, but it seems there is similar damage, although at much smaller scale, right across the coin at 6 o'clock. One explanation could be that the coin was set in a frame and those marks indicate the spots where it was held by small clips to prevent the coin's movement and rotation in the frame. The cuts could have been made either to help the coin be held more firmly in the frame, or when removing the coin from it.
In any case, the edge looks otherwise perfect and the coin face does not bear any typical signs of being ex-mount such as excessive polishing. How does the reverse look like?
Also, I have a French Ecu coin in my collection with very similar cut to its edge and my theory about it at one point was that it was made to check if the coin was solid silver and not just silver-plated. But, with an object over 200 years old, anything could have been happening with it during all that time...