Still seem to have the same issue. Downloaded latest xvfb.hpi, and restarted Jenkins. PluginManager states version 1.0.5.
Job on first executor still gets the display :0, and a job running at the same time on the second executor gets display :1.
The jobs are building on a node/slave.
Running on Jenkins version 1.486.
Also: The text field itself is always empty, i e if I set a value, and applies the change then reload the page, the text field is empty.
A svn diff on the config.xml shows, when manually setting the value to 1: