WASHINGTON — It’s a rare occurrence to play any team in the NHL twice in six days, but especially when it’s a club from the other conference. The NHL schedule makers have provided an interesting opportunity Thursday night for the Colorado Avalanche. The Avs will get a second crack at the Eastern Conference-leading Washington Capitals in less than a week. They will have a chance to measure themselves against one of the league’s best outfits, though the Capitals will be missing a huge piece.