It was a quiet half for Blackpool keeper Barnes but he had to back pedal to hold Durnin's lob under his crossbar in the 67th minute.
But Harriers custodian Clarke was far busier and had to block a shot from Ormerod on 72 minutes as the striker again dissected the visitors' defence.
Blackpool brought on Neil Murphy and Richard Walker for Tommy Jazsczun and hat-trick hero Murphy 10 minutes from time.
Harriers were further embarrassed on 85 minutes when Ormerod eased past Mark Shail and finished expertly after a walker thought pass.
The home side brought on their final sub three minutes from time when Phil Clarkson replaced Ormerod.
The Blackpool fans in the crowd of 4,624 gave their side a standing ovation at the end after completing a Division Three double over the Harriers visitors.
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