Creating transaction using icontrolrest on version 11.5.1 virtual f5 seems to throw an error

Hi,

When I create multiple transactions for different operations, the first one seems fine but the second transaction creation throws an error.

Transaction 1

curl -k https://[F5]/mgmt/tm/transaction -u admin:admin -X POST -H "Content-type: application/json" --data "{}"
{
  "transId": 1456370986,
  "state": "STARTED",
  "timeoutSeconds": 30,
  "kind": "tm:transactionstate",
  "selfLink": "https://localhost/mgmt/tm/transaction/1456370986?ver=11.5.1"
}

Transaction 2

curl -k https://[F5]/mgmt/tm/transaction -u admin:admin -X POST -H "Content-type: application/json" --data "{}"
{
  "code": 400,
  "message": "A transaction id 1456370986 for the user has already created.",
  "errorStack": []
}

Please shed some light?