Libbitcoin does not exhibit the recent bitcoind (Core, et. al.) consensus bug or DoS bug pertaining to internal double spend checks.

https://bitcoincore.org/en/2018/09/20/notice/

As these checks do not require chain state they are performed in a context-free manner.

https://github.com/libbitcoin/libbitcoin/blob/version3/src/chain/transaction.cpp#L923

https://github.com/libbitcoin/libbitcoin/blob/master/src/chain/block.cpp#L641

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