1757 8 Reales, Auguste Shipwreck 1761

There are two styles for the edge, depending on the period :
* details all go in the same direction, and there are two overlaps - each at the exact opposite (12 hours appart)
* details go in opposite directions, and there are two overlaps - each at the exact opposite (12 hours appart).

In the second case, it's very easy to spot the overlap, as the pattern go to the opposite direction in two places :)
In the first case, the pattern sometime overlaps almost perfectly and it can be hard to see.

If you have that feature, it's a good tip to not mark your coin as fake :) (most fakes don't have this)

If your coin is Mexico or Guatemala mint then it is normal for a 1757 to have the edge design change direction as mentioned above. Those mints produced coins with edge design all one direction and coins with edge design changing direction mid way, but only on coins dated before 1764.