SALEM (AP) — Two lawsuits challenging Oregon tax law have the potential to blow a big hole in the state budget. One suit targets Measure 67 and could open the door for some corporations to erase or reduce their higher tax bills from the three-year-old ballot measure. The other lawsuit challenges an obscure state tax law that has resulted in higher taxes for some multi-state corporations. The price tag for the Measure 67 case is low by budget standards: about $6 to $12 million a year after an initial hit of $20 million in refunds for prior years. But legislative …