Spark shows twice a message without the type attribute.
Notice the type attribute is a recommendation but not a MUST.
It was reported in http://www.igniterealtime.org/forum/thread.jspa?threadID=26921
How to reproduce:
1- Go to Ad-Hoc message and send
<message to="email@example.com" type="chat" from="firstname.lastname@example.org/sendxmpp"><body>test123</body><subject/></message>
2- Notice that user1 receives a broadcast and message.