bitcoin/bitcoin — pull request #2366 by zechiel (2013-03-14 01:48:59+00:00)
Title: Allow createrawtransaction to accept duplicate addresses

As discussed on the #bitcoin-dev IRC channel, enforcing unique addresses in sendmany is useful because it may prevent the user from accidentally paying somebody twice. If you really want to, it should be possible to include the same address multiple times using the rawtransaction commands, though.