Distributed transaction failure when using JTS, EJB Remoting and Oracle XA resources in EAP 6

Issue

• In a CMT bean, on "server01" use Oracle XA datasource "pool1"
• Invoke a remote method on an EJB (hosted by "server02") which accesses Oracle XA datasource "pool1" and "pool2"
• The transaction fails on "server02" with

... ARJUNA024046: TransactionImple.enlistResource - XAResource.start returned XA error XAException.XAER_RMFAIL for transaction < ... >: oracle.jdbc.xa.OracleXAException

• Oracle driver tracing reveals that the underlying error is

ORA-24757: duplicate transaction identifier

• The transaction subsequently fails on "server01" with the following two errors

... ORA-02051: another session or branch in same transaction failed or finalized
... javax.transaction.RollbackException: ARJUNA016053: Could not commit transaction.