don't inherit fields for tags that the preset already has a field for

this is useful if a preset wants to inherit some fields from another preset, but wants to replace some of the fields with special versions of the field (e.g. a `…_yes` field for an added default value), or to change the `fields`/`moreFields` classification of a field

CHANGELOG.md

@@ -49,6 +49,8 @@ _Breaking developer changes, which may affect downstream projects or sites that
 #### :earth_asia: Localization
 #### :hourglass: Performance
 #### :mortar_board: Walkthrough / Help
+#### :rocket: Presets
+* Don't inherit fields which the current preset already has a dedicated field for
 #### :hammer: Development
 
 [#10805]: https://github.com/openstreetmap/iD/pull/10805

modules/presets/preset.js

@@ -325,7 +325,7 @@ export function presetPreset(presetID, preset, addable, allFields, allPresets) {
       }
     }
 
-    return utilArrayUniq(resolved);
+    return resolved;
 
 
     // returns an array of fields to inherit from the given presetID, if found
@@ -335,7 +335,7 @@ export function presetPreset(presetID, preset, addable, allFields, allPresets) {
       if (which === 'fields') {
         return parent.fields().filter(shouldInherit);
       } else if (which === 'moreFields') {
-        return parent.moreFields();
+        return parent.moreFields().filter(shouldInherit);
       } else {
         return [];
       }
@@ -349,6 +349,11 @@ export function presetPreset(presetID, preset, addable, allFields, allPresets) {
         // inherit anyway if multiple values are allowed or just a checkbox
         f.type !== 'multiCombo' && f.type !== 'semiCombo' && f.type !== 'manyCombo' && f.type !== 'check'
       ) return false;
+      if (f.key && (_this.originalFields.some(originalField => f.key === allFields[originalField]?.key)
+             || _this.originalMoreFields.some(originalField => f.key === allFields[originalField]?.key))) {
+        // current preset already has a field for this field
+        return false;
+      }
 
       return true;
     }