Tx with sender=recipient shows twice in api result

If i send tx from A to A /transactions/address/{address} will return such tx twice.

ps. you can see this result for [this tx](http://testnet.wavesexplorer.com/tx/5X5c7cSCxHNtcMXEfJoe7kiYdE6q8EXfTwKFBk8GSmdP3X6UTGj6Rb6AHXrJViWKwYRoBZiGTXKVzM8xVHnDBPGN) if click on Sender address

Start at the /transactions/address/{address} API entry point and reproduce the sender=recipient case using the linked transaction or an equivalent test transaction. Trace how transactions are collected for sender and recipient, then add or update a regression test. Done means a self-sent transaction appears once in the API result.

Written by the indexing model from the issue text.