OUSTON, June 22 — The Enron Corporation used undisclosed reserves to keep as much as $1.5 billion in trading profits off its books during the California energy crisis, according to six former managers and executives who handled or reviewed the accounts.The enormous reserves, which would have doubled the company's reported profits, were hidden in late 2000 and early 2001, as energy prices soared in California and politicians accused trading companies like Enron of price gouging. The former Enron officials said that the company swelled the reserves in hopes of damping the political firestorm.Further, some former executives said, Enron manipulated...