That time, the margin was also two points.
Played in difficult conditions with rain falling for much of the game, both teams delivered an entertaining match.
The home side led 10-2 at halftime with tries to in-form winger Marika Koroibete and Cooper Cronk.
Halfback Cronk was only cleared to play following their final training session after spending the week in bed with flu.
He and Cherry-Evans waged a battle all game, with both standouts among their sides.
Koroibete also had a busy night, repeatedly testing the Sea Eagles' defensive line.
He left the field temporarily with 15 minutes remaining for a concussion test after he made a break and was brought down in a three-man tackle, with fullback Brett Stewart put on report for his contribution.
Sea Eagles centre Steve Matai was also put on report in the first half for an alleged high tackle on his Storm opposite Will Chambers.
Manly's other try was scored by lock Tom Symonds after the Storm were repeatedly penalised for slowing down the play the ball.
That closed the gap to 10-8 before Williams nudged his side ahead.
- AAP