Using jboss 4.2.1 (based on tomcat 5.5), with tomcat-native-1.1.10 installed, and SSL enabled. Connecting to port 8443 (https port) using netcat and then disconnecting without sending any data will cause tomcat to handle a duplicate copy of one of the recent requests. For example, a client at 10.0.0.1 is making HTTP GET requests for https://someserver:8443/someurl?foo=1, with foo being incremented on each request. If you connect to the https port from 10.0.0.2 and then disconnect without sending any data, the access log will show 10.0.0.2 issuing a request for someurl?foo=some_recent_number.
This has been fixed in svn and will be included in native 1.1.12 onwards.