diff --git a/test/api/v3/integration/groups/PUT-groups.test.js b/test/api/v3/integration/groups/PUT-groups.test.js
index 36bdfdd7d4..77d4ad6487 100644
--- a/test/api/v3/integration/groups/PUT-groups.test.js
+++ b/test/api/v3/integration/groups/PUT-groups.test.js
@@ -11,6 +11,12 @@ describe('PUT /group', () => {
   const groupName = 'Test Public Guild';
   const groupType = 'guild';
   const groupUpdatedName = 'Test Public Guild Updated';
+  const groupCategories = [
+    {
+      slug: 'initialCat',
+      name: 'Initial Category',
+    },
+  ];
 
   beforeEach(async () => {
     const { group, groupLeader, members } = await createAndPopulateGroup({
@@ -18,6 +24,7 @@ describe('PUT /group', () => {
         name: groupName,
         type: groupType,
         privacy: 'public',
+        categories: groupCategories,
       },
       members: 1,
     });
@@ -61,6 +68,35 @@ describe('PUT /group', () => {
     expect(updatedGroup.categories[0].name).to.eql(categories[0].name);
   });
 
+  it('removes the initial group category', async () => {
+    const categories = [];
+
+    const updatedGroup = await leader.put(`/groups/${groupToUpdate._id}`, {
+      categories,
+    });
+
+    expect(updatedGroup.categories.length).to.equal(0);
+  });
+
+  it('removes duplicate group categories', async () => {
+    const categories = [
+      {
+        slug: 'newCat',
+        name: 'New Category',
+      },
+      {
+        slug: 'newCat',
+        name: 'New Category',
+      },
+    ];
+
+    const updatedGroup = await leader.put(`/groups/${groupToUpdate._id}`, {
+      categories,
+    });
+
+    expect(updatedGroup.categories.length).to.equal(1);
+  });
+
   it('allows an admin to update a guild', async () => {
     const updatedGroup = await adminUser.put(`/groups/${groupToUpdate._id}`, {
       name: groupUpdatedName,
diff --git a/website/server/controllers/api-v3/groups.js b/website/server/controllers/api-v3/groups.js
index cfa582ecd9..c16ba61c7e 100644
--- a/website/server/controllers/api-v3/groups.js
+++ b/website/server/controllers/api-v3/groups.js
@@ -492,7 +492,17 @@ api.updateGroup = {
 
     if (req.body.leader !== user._id && group.hasNotCancelled()) throw new NotAuthorized(res.t('cannotChangeLeaderWithActiveGroupPlan'));
 
-    _.assign(group, _.merge(group.toObject(), Group.sanitizeUpdate(req.body)));
+    const handleArrays = (currentValue, updatedValue) => {
+      if (!_.isArray(currentValue)) {
+        return undefined;
+      }
+
+      // Previously, categories could get duplicated. By making the updated category list unique,
+      // the duplication issue is fixed on every group edit
+      return _.uniqBy(updatedValue, 'slug');
+    };
+
+    _.assign(group, _.mergeWith(group.toObject(), Group.sanitizeUpdate(req.body), handleArrays));
 
     const savedGroup = await group.save();
     const response = await Group.toJSONCleanChat(savedGroup, user);