Hi Jens,
To add to what IC has written, on Linux, the EMS runs with multiple internal processes. These processes create streams between the processes in an edge-origin type paradigm. The streams that you see which have a large uniqueIDs are those internal streams.
A (not very obvious, but) simple test is to see if the UniqueID value is greater than: 0x1 0000 0000.
We will be introducing a new flag for the listStreams function in our next release which will allow you to automatically filter out all of these "internal" streams. This will hopefully simplify your situation.