Clue for 1-Across isn't quite accurate—duals are multiple solutions to a problem, not multiple problems.
1 D  | 2 U  | 3 A  | 4 L  | 5 S  | 6 T  | 7 U  | 8 B  | 9 E  | 10 I  | 11 M  | 12 E  | 13 T  | 
		||
14 E  | N  | R  | O  | L  | 15 O  | R  | A  | L  | 16 D  | U  | M  | B  | 
		||
17 C  | U  | C  | K  | O  | 18 O  | P  | I  | N  | T  | 19 I  | N  | C  | A  | 
		|
20 S  | H  | I  | V  | S  | 21 S  | T  | O  | 22 O  | D  | E  | R  | 
		|||
23 A  | I  | 24 T  | 25 U  | N  | 26 I  | T  | I  | E  | S  | 
		|||||
27 S  | 28 H  | 29 O  | 30 C  | K  | E  | R  | 31 S  | 32 S  | A  | C  | ||||
33 P  | A  | R  | R  | 34 R  | E  | C  | 35 S  | 36 G  | A  | 37 L  | 38 A  | 39 S  | 
		||
40 A  | L  | S  | A  | 41 B  | 42 N  | A  | T  | 43 O  | R  | A  | L  | E  | 
		||
44 S  | E  | I  | Z  | E  | 45 T  | R  | O  | 46 T  | 47 D  | I  | M  | E  | 
		||
48 Y  | A  | 49 W  | 50 F  | O  | O  | 51 L  | S  | C  | A  | P  | 
		||||
52 C  | 53 A  | 54 S  | Q  | U  | E  | 55 S  | 56 D  | D  | E  | |||||
57 A  | T  | T  | U  | 58 E  | M  | 59 E  | 60 A  | T  | 61 O  | 62 M  | 63 S  | |||
64 N  | E  | R  | I  | 65 D  | I  | Z  | 66 Z  | Y  | T  | R  | O  | U  | 67 T  | 
		|
68 E  | T  | A  | L  | 69 E  | T  | R  | E  | 70 E  | L  | O  | P  | E  | 
		||
71 S  | E  | P  | T  | 72 R  | E  | A  | D  | 73 R  | E  | S  | E  | T  | 
		
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Answer summary:
4 unique to this puzzle,  5 appeared only in pre-Shortz puzzles.
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Crosswords published prior to Nov. 21, 1993 are provided by David Steinberg and The Pre-Shortzian Puzzle Project.