Hejda's tally off a pass through the crease from Ryan O'Reilly broke a 2-2 tie 10:20 into the third period, and Galiardi's slap shot 2 1/2 minutes later gave the Avs an insurance goal.
O'Reilly and Gabriel Landeskog also scored as Colorado notched its fifth straight victory.
Semyon Varlamov earned the victory with 20 stops, including all nine in the third period.
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