A darn pity to let this great thread go empty so I'll post mine too:
(btw, that 1731 denga is hot - normally you would think that legend around that eagle is part of the design")
1731 polushka over 1728 Peter II kopek

1730 denga over ? Peter I kopek

1730 denga over 1717 Peter I kopek

1731 denga over 1724 Peter I kopek (uncommon!!!)

1731 denga over 1716 MD? Peter I kopek

With such huge amount of overstriking occuring, I am not too sure if any silver coins of Anna were overstruck. I am quite sure that at least a few did pass through the overstriking stages, only waiting to be found.
Great thing is usually these coins are rather cheap only if you know how to identify them. (with the exception of that overstruck 1724 kopek)