VANCOUVER, British Columbia — Here we go again. A week ago, on what was called Super Sunday, the Americans beat the Canadians in the Olympics for the first time in 50 years. On Sequel Sunday, the U.S. will try to become Olympic champions on the 50th anniversary of their out-of-nowhere gold medal in Squaw Valley, Calif.; the only other American hockey gold was the Miracle on Ice in Lake Placid 30 years ago. No, one game wasn’t nearly enough. Canada, the hockey superpower, was always was supposed to play for the gold medal on home ice in the very country that invented hockey. The United States, the infrequent power that hasn’t won a hockey gold outside its own borders, has been the best team in the Olympics so far. Beating Canada on Canadian ice with a pro-Canadian crowd once was difficult enough for the U.S., the surprise of the tournament and the only unbeaten team remaining. ‘‘It’s hard to be a team twice in a tournament like this,’’ U.S. coach Ron Wilson said.