Like mentioned earlier, the only difference in the domains was a dash (-) in the domain name. What had happend was that Google would index the domain with a dash, it received a PR5 and stayed with it for a while. Nowhere in the index did it have the domain without a dash. Then, on a
PR update the dash domain lost a
PR (went down to PR4)... that made me think. Did some research and turned out that Google was indexing the non-dash domain now. Some time later, the non-dash domain received a PR2 and other domain stayed at PR4. (Would probably help to mention that Yahoo and MSN indexed the non-dash domain the whole time, never picked up the one with a dash). Anyway, after that it just went downhill and once we did the re-direct the two domains stayed at a PR2...