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The other Piggy uses its own blockchain, the one in your Ethereum wallet is "mine".

is it possible to sell my coins ? @drpig

Sure, you can sell them on EtherDelta: https://etherdelta.com/#0xc6b1953ab35f05db745dadd5ce411d75758a7898-ETH (at current prices, though, it's more fun to hodl them :))