Which PMD rules to activate for JUnit tests?

Question

I'm in the middle of setting up PMD as a tool in our team to support us writing better code. Basically I'm building Ant scripts and try to set up some rules for everyone to use.

But right now I hit this problem:

When I write JUnit tests I don't want to use the same rules I apply on our main source code. I don't care that much about String rules (like string dupliates or weird instantiations) in the junit tests.

My questions is:

1. Is that a fault on my side and should I start writing better JUnit tests?
2. Should I provide a 2nd set of rules that disables some of the string/design/finalizers rules?