add exception for dual names

src/stage3-conflate/compareFeatures/__tests__/compareFeatures.test.ts

@@ -378,7 +378,9 @@ describe('compareFeatures', () => {
         ),
       ).toStrictEqual({ natural: 'spring' }); // default preset is suggested
     });
+  });
 
+  describe('exceptions', () => {
     it.each`
       nzgb              | osm
       ${'Saint Martin'} | ${'St Martin'}
@@ -389,4 +391,16 @@ describe('compareFeatures', () => {
       expect(conflateTags({ name: nzgb }, { name: osm })).toBeUndefined();
     });
   });
+
+  it('allows dual names in the name tag', () => {
+    expect(
+      conflateTags(
+        { name: 'Ōmanawa Falls' },
+        {
+          name: 'Te Rere o Ōmanawa / Ōmanawa Falls',
+          'name:mi': 'Te Rere o Ōmanawa',
+        },
+      ),
+    ).toBeUndefined();
+  });
 });

src/stage3-conflate/compareFeatures/compareFeatures.ts

@@ -5,6 +5,7 @@ import type { NZGBFeature, OSMFeature } from '../../types';
 import { createDiamond, distanceBetween } from '../../core';
 import { DONT_TRY_TO_MOVE, NZGB_NAME_TYPES, __SKIP } from '../../data';
 import {
+  allowDualNames,
   allowSlashInsteadOfOr,
   allowTrivialDifferences,
   isUnofficialAndOsmHasMacrons,
@@ -44,6 +45,7 @@ export function compareFeatures(
       isUnofficialAndOsmHasMacrons(nzgb, osm),
       allowSlashInsteadOfOr(nzgb, osm),
       allowTrivialDifferences(nzgb, osm),
+      allowDualNames(nzgb, osm),
     ];
     // if every exception is false, then propose changing the name
     if (exceptions.every((x) => !x)) {

src/stage3-conflate/compareFeatures/exceptions.ts

@@ -62,3 +62,18 @@ export function allowTrivialDifferences(nzgb: NZGBFeature, osm: OSMFeature) {
     normaliseTrivialNameDifferences(osm.tags.name || '')
   );
 }
+
+/**
+ * Allow name:mi to be repeated in the name tag for dual names
+ * that are separated by a `/`
+ */
+export function allowDualNames(nzgb: NZGBFeature, osm: OSMFeature) {
+  const nameSegments = osm.tags.name?.split(' / ');
+
+  return (
+    nameSegments?.length === 2 &&
+    nameSegments.every(
+      (segment) => segment === nzgb.name || segment === osm.tags['name:mi'],
+    )
+  );
+}