The Warsaw Pact fielded a tracked version of the ZSU-57-2 for many years. Not strictly a tank but at first blush appears tobe a tracked armored vehicle with two barrels. The conical flash surpressors are a key identification feature.
http://armyreco.ifrance.com/russe/ve..._russia_03.jpg
I have seen a lot of these as gate guardians and static displays. And a few as airfield defense weapons in sub Saharan Africa.