Deploying wars in same ear to multiple context-roots

I would like to deploy two instances of the same ear to one weblogic 10 instance
(the ear contains two wars). The problem is that I haven't found a way to
override the context root defined in application.xml. I would like to use
exactly the same ear without needing to edit application.xml inside it, but just
to be able to deploy it twice and change the context roots.

I tried to replace the context-root in application.xml using deployment
descriptor, but it didn't work out:

<xpath>/application/module[@id="WebModule_1"]/web/context-root&l
t;/xpath>
<operation>replace</operation>

But the result is just a bunch of validation errors.