Vaadin portlet deployed on multiple pages sharing state

From experimentation it appears that deploying the same portlet instance on multiple pages still results in independent Vaadin application instances. From what I can tell the portlet instances are indeed shared but the Vaadin applications running inside of the shared portlet instance are definitely different.

We have a use case where it would be ideal if the same Vaadin application instance was shared between these portlets if this is possible to do.

This is for IBM WebSphere 6.1 if it makes any difference.

Any advice?