Just out of curiosity, which part of HealthShare are you running these queries? Are you looking on the Access Gateway, Edge Gateway, Registry?
They all use the same message structure, but in different parts of the "request/response" cycle. The "facing the outside world" context is the Access Gateway, the rest are more "internal to Information Exchange" propagating of the request and motivating the various parts to gather the response, so it's quite likely that (as Justin mentioned) there can be replications of the message content into "new message" records that are NOT actual "new requests".
When you look directly at the SQL table outside of the context of the complete message trace (i.e. a "Session") it should be expected that you will see what appears to be exactly the same content in multiple messages in the table.