The Senate voted yesterday for a second time to give the president emergency oil allocation authority that he has indicated he doesn't want.

The Senate adopted a conference committee report on the Standby Petroleum Allocation Act of 1982 by a vote of 86 to 7, a margin large enough to suggest an override if the president should veto the bill. The House of Representatives also is expected to adopt the conference report.

The bill gives the president broad discretion to determine if a severe petroleum supply shortage exists and, if so, whether to allocate supplies and control prices. It also requires that a standby plan be prepared to have on hand for an emergency.

The standby authority act would expire at the end of Ronald Reagan's first term.

"It's inconceivable to me that the president could say 'don't give me discretionary power to be used in the event of an emergency'," said Sen. J. Bennett Johnston (D-La.). "He need not use it if he doesn't want to under any circumstances."

Past experience with oil supply disruption indicates that the free market may not respond fast enough to certain critical needs, said Sen. James A. McClure (R-Idaho), chairman of the Energy and Natural Resources Committee. Without legislation of this sort, consumers might begin hoarding in a shortage, fearful that badly needed oil might be bid away from them, he said. He also defended the bill as a national solution to a national problem.

Sen. Don Nickles (R-Okla.), who opposed the bill, urged the president to veto it. "Very simply put, this bill will do more damage than good in the event of a petroleum shortage," Nickles said.