Why are my messages consumed by a stomp client received out of order?

Issue

We have a stomp client produces messages, JMS consumer reads messages. The send and receive are performed sequentially, we'd expect all messages in groups b, c, d, & e to be read in order instead of interleaved, i.e. we are seeing:

Messages sent, now attempting to consume...
431  [main] DEBUG org.apache.activemq.TransactionContext  - Begin:TX:ID:icbts.local-59880-1354298369587-1:1:1
GroupSeqId 1:Msg# 1 in GroupID-b:GroupID-b
GroupSeqId 1:Msg# 1 in GroupID-c:GroupID-c
GroupSeqId 2:Msg# 2 in GroupID-b:GroupID-b
GroupSeqId 2:Msg# 2 in GroupID-c:GroupID-c
GroupSeqId 3:Msg# 3 in GroupID-c:GroupID-c
GroupSeqId 3:Msg# 3 in GroupID-b:GroupID-b
GroupSeqId 4:Msg# 4 in GroupID-b:GroupID-b
GroupSeqId -1:Msg# 5 in GroupID-b:GroupID-b
GroupSeqId 4:Msg# 4 in GroupID-c:GroupID-c
GroupSeqId -1:Msg# 5 in GroupID-c:GroupID-c
GroupSeqId 1:Msg# 1 in GroupID-d:GroupID-d
GroupSeqId 2:Msg# 2 in GroupID-d:GroupID-d
GroupSeqId 3:Msg# 3 in GroupID-d:GroupID-d
GroupSeqId 4:Msg# 4 in GroupID-d:GroupID-d
GroupSeqId -1:Msg# 5 in GroupID-d:GroupID-d
GroupSeqId 1:Msg# 1 in GroupID-e:GroupID-e
GroupSeqId 2:Msg# 2 in GroupID-e:GroupID-e
GroupSeqId 3:Msg# 3 in GroupID-e:GroupID-e
GroupSeqId 4:Msg# 4 in GroupID-e:GroupID-e
GroupSeqId -1:Msg# 5 in GroupID-e:GroupID-e
Test case complete.