Duplicate cache names shouldn't be allowed

Multiple caches with the same name can be defined without a WARN/ERROR message.
It's also unclear which one will be used, for example with this configuration

<distributed-cache name="testCache"/>
<distributed-cache name="testCache">
    <eviction max-entries="100" />
</distributed-cache>
<distributed-cache name="testCache"/>

the cache with eviction will be used. Actually the configurations are merged...