The bitcoind sendmany RPC call uses destination addresses as JSON Object keys, so you can't send to the same address multiple times in one transaction.
If you REALLY want to do that... first, why do you want to do that? I suppose if you want to use the blockchain as a messaging system then sending 0.123+0.567+etc might be an inefficient way of sending a message... but please don't do that.
Anyway, if you do REALLY want to do that, you'll have to write code to construct the transaction yourself. Then you could pass it to the signrawtransaction/sendrawtransaction RPC methods to broadcast it. (you can't use createrawtransaction to create it, because it uses the same JSON syntax as sendmany for destination outputs).