Mulgrave posted an impressive 249-6, Duell leading the way with a sparkling 90 from 92 balls, Simon Kipling scoring a brilliant 67 and Chris Spenceley 48.
Duell and Spenceley put on 85 for the second wicket, while Duell shared an 114-run stand for the third wicket with Kipling.
Duell then dislodged three of the top four Scalby batsmen in his 3-32 in 10 overs as the visitors were dismissed for 164.
Openers Tim Piper (43) and Lee Kerr (37) gave the away side a solid start but their teammates struggled to get going with the bat.
Seamer & Irton 2nds secured a four-wicket triumph at home to Wykeham 2nds despite a brilliant all-round performance from the visitors' Chris Kirkham-Knowles.
Liam Lowery scooped 4-22 as the visitors were dismissed for 129, Reggie Steels and veteran Paul Greenhough taking two wickets each.
Kirkham-Knowles' 48 and an unbeaten 30 from skipper Gareth Barnard helped keep Wykeham in the contest.
Former Newby & School head teacher Kirkham-Knowles then taught the Seamer batsmen a lesson with cracking figures of 5-28 from 4.4 overs as Seamer slipped from 89-1 to 116-5, but a forceful 86 from opener Matt Pearson, including 15 fours and two sixes, helped the hosts to a winning 132-6 from just 21.4 overs.
Will Bradley's excellent spell of 6-15 steered leaders Ganton to a 10-wicket win at Nawton Grange.
The hosts were skittled for 74 in 35.2 overs, Anton Wessels (14) the only batter to make it into double figures.
Openers Robbie Milner (42no) and Jack Heslehurst (19no) steered Ganton to victory from only 20.1 overs.
]Ben Norman put in a strong all-round display as Snainton won by eight wickets at struggling Glaisdale.
Norman took 2-10 in 10 overs as the hosts posted 191-8, Michael Kipling bagging 3-49 and Kieran Jackson 2-47.
Opener Martin Thistle top-scored with 67, while William Burtt (35) and skipper Tom Wardell (29) also chipped in.
Norman then hammered a top score of 77 and opener Mike Eyre 73 as Snainton secured success with 13.4 overs and eight wickets to spare.
Cayton 2nds are third after Settrington conceded their game.
Grosmont halted Flamborough's 100% start to the Division Three season, the hosts seeing off the leaders by three runs in a thriller.
Opener Anthony Clarkson led the way with 46 as Grosmont posted 113-9, Jack Carradice-Clarkson snapping up 4-19 and Harry Burton 3-7.
Matt Emmerson (39) and Carradice-Clarkson (19) tried their level best to guide Boro to victory but they were skittled for 110 with 10 balls remaining, Chris Pickering scooping 3-10, Clarkson 2-18 and Charlie Parker 2-15 as Grosmont completed a thrilling win.
James Buckley took a superb 5-11 and hit a brilliant 64no as third-placed Goathland won by 10 wickets at Scarborough Rugby Club.
The hosts were all out for 116 thanks to Buckley's top bowling, and the latter then shared an unbroken opening stand of 120 for the first wicket with skipper Liam Calvert (43no).
Muston won by 42 runs in a low-scoring contest at Wold Newton.
Koppy Harrison snapped up 3-9, Simon Moore 3-29 and Toby Robson -Brown 3-29 as Muston were dismissed for 79 in 33 overs.
But any hopes of Newton claiming victory were soon dashed as they collapsed to 8-7 and were eventually all out for 37 in 34.4 overs, number nine bat Steve Ward (13) the only one to reach double figures.
Dave Meer scooped a superb 4-16 from nine overs and Tom Sanders 3-1 from eight overs as Muston bowlers ran riot.
Jish Rewcroft took 4-12 as Ravenscar won by six wickets at home to Great Habton 2nds.
Ten-man Habton were skittled for 71 runs in 29.1 overs, Firoz Ghafori weighing in with 2-14 and Nisar Hassanzadeh 2-7, Vernon Smith the only Habton batter to get going with 24.
Robin Coulson's 24 helped the hosts to a winning 76-4 from 18.5 overs.
Filey 2nds romped to a 157-run victory at home to Folkton & Flixton 3rds, and the Clarence Drive-based team then won by six wickets at Muston on Sunday.
Brompton 2nds eased to an eight-wicket Division Four success at Forge Valley 2nds.
Alex Bennett scooped an excellent 3-7 from 8.5 overs, Phil Holden 3-40, Tony Hulme 2-22 and Dan Reardon 2-1 as Valley were skittled for 86, Aaron Kaya top-scoring with 34.
Reardon capped a fine individual display with an impressive 50no as he and fellow opener Robin Siddle (31) helped Brompton to a winning 90-2 from 18.2 overs.
On Sunday, Sherburn 2nds romped to a 107-run win at 10-man Staxton 2nds.
Matthew Lickes led the way with an excellent 87no as the visitors racked up 235-8, Lenny Goncalves and Jordon Farrow hitting 38 apiece and Ash Oldroyd 31.
Leon Stafford was the top Staxton bowler with 3-33.
Ben Simpson's 4-24 then helped dismiss the home side for 128 from 26 overs, despite a fine unbeaten 42 from Steve Hill and cameos from Paul Russell (27) and Tommy Atkinson (28).
Malton & Malton 3rds edged to a one-wicket success at Pickering 3rds, also on Sunday.
Lewis Bennison took 3-33 as the Pikes posted 143-6, the in-form Macauley Gibson leading the way with an excellent 62no, supported well by Nathan Brown's 23.
Archie Lythe's 4-30 looked to be sending Malton crashing to defeat, but opener Alistair Blacklee (25) and Ross Harland (22) helped the visitors edge to a winning 146-9
Will Holborn was the all-round hero as Scalby 3rds won by 21 runs on the road at Malton & Old Malton 4ths in Division Five.
Number 10 bat Holborn struck 26 and opener Josh Lowe 34 as the visitors posted 132-9, Jonny Tyson the top Malton bowler with 3-24.
Holburn then snapped up a superb five-wicket haul, and Tash Turan three wickets, as Malton were all out for 111 despite plucky efforts from Tom Tyson (22no) and Harry Johnson (26).
Wykeham 3rds are top of Division Five after they won by three wickets at home to Forge Valley 3rds.
George Jackson took 3-3 and Darrell Trousdale 3-19 as Valley were all out for 87 in 25.2 overs, skipper Byju Ousephutty top-scoring with 38.
Veteran Steve Brennan's 25 in reply proved crucial as Wykeham made it to a winning 88-7 from 32.4 overs, Ousephutty completing a fine personal performance with top figures of 4-17 in six overs.
Second-placed Nawton Grange 2nds earned a three-wicket win at Thornton Dale 2nds.
Liam Wood took 3-17 as Dale only made it to 116-6, John Kinghorn top-scoring with 24.
Paul Elgey (3-33) gave Grange a few worries after openers Wood (46) and Liam Thwaites (29) had done the early work for Grange.