UIMA AS: Duplicate Request

Hi,

there is this message in the service logs:
1/29/10 3:09:40 AM - 16:

org.apache.uima.aae.handler.input.ProcessRequestHandler_impl.handleProcessRequestFromRemoteClient: 
INF
O: Duplicate Request With Cas Reference Id: 2d0e21bb:12664a22384:7eac 
Received. Ignoring Duplicate.

What does it mean ? And how can it happen ?

Jörn