Some of the coins shown on the page you linked to appear to have 2 dots.
I checked my
Cyzicus coins and found one with what appeared to be 2 dots on the
chlamys --
Maximianus,
RIC 12b.
The photo was taken with the light coming from what is the top of the picture, and yes, it appears to be dots or pellets in the
chlamys.
A close-up photo with the light coming from what is the left
side of the picture, shows something different. Perhaps they are meant to represent twists in the
fabric of the
chlamys.
