In theory yes, Logic can handle serveral audioengines at the same time. You just need to make sure that the cards' sampleclocks are syncronized. (Via SP-Dif)
But why on earth would you want to keep the AudioWerk in such a setup ??????
well its gona take time before i get my Pulsar II and Scope 3 more weeks for it to arrive to me .. so i said il use a Audiowork till then .. so i just thought of using them both together .. well i know im not gona do that .. but thanks anyways