The WordPress plugin "Fix Duplicates" [ https://wordpress.org/plugins/fix-duplicates/ ] tests for duplication by title. In my situation, we'd inadvertently double-imported some posts, but had a lot of different posts with the same titles, so I needed a way to see which ones were truly duplicates (based on having the same timestamp) vs. just the …

Reveal date-matched duplicates.js

jQuery( 'table.wp-list-table.widefat.fixed.posts tr' ).css( 'display', 'table-row' );
jQuery( 'tbody[id^="fix-duplicates-group-"]' ).each( function() {
	var rowWrapper = jQuery( this );
	var matchingDateCount = 0;
	var dates = new Array();
	var matchedDates = new Array();
	var dateCount = rowWrapper.find( 'tr td.date abbr' ).length;

	rowWrapper.find( 'tr td.date abbr' ).each( function() {
		var currentDate = jQuery( this ).text();
		
		if ( -1 !== dates.indexOf( currentDate ) ) {
			matchingDateCount++;
			matchedDates.push( currentDate );
		} else {
			dates.push( currentDate );
		}
	});

	// Color sections where all dates match
	if (
		0 < matchingDateCount &&
		dateCount === ( 1 + matchingDateCount )
	) {
		rowWrapper.find( 'tr' ).css( 'background-color', 'deepskyblue' );
	} else if ( 0 < matchingDateCount ) {
		for ( i = 0; i < matchedDates.length; i++ ) {
			rowWrapper.find( 'tr td.date abbr:contains(' + matchedDates[i] + ')' ).each( function() {
				jQuery( this ).css( 'background-color', 'orange' );
			});
		}
	} else {
		rowWrapper.find( 'tr[class^="duplicate-group-"]' ).css( 'display', 'none' );
	}
});