don't repeat values from multi-selection in dropdown

as their state can now been toggled using the checkbox in the chip

CHANGELOG.md

@@ -37,7 +37,7 @@ _Breaking developer changes, which may affect downstream projects or sites that
 
 # Unreleased (2.26.0-dev)
 #### :tada: New Features
-* Combo fields for tags with `yes/no` values now correctly display the `no` state and allow to toggle between the two states ([#7427])
+* Combo fields for tags with `yes/no` values now also display the `no` state and allow to toggle between the two states ([#7427])
 #### :sparkles: Usability & Accessibility
 * Make it easier to search for OSM objects by id ([#9520], thanks [@k-yle])
 #### :scissors: Operations

modules/ui/fields/combo.js

@@ -151,7 +151,7 @@ export function uiFieldCombo(field, context) {
     function objectDifference(a, b) {
         return a.filter(function(d1) {
             return !b.some(function(d2) {
-                return !d2.isMixed && d1.value === d2.value;
+                return d1.value === d2.value;
             });
         });
     }