diff --git a/packages/client-sync/src/local-sync-worker/sync-tasks/fetch-folder-list.imap.es6 b/packages/client-sync/src/local-sync-worker/sync-tasks/fetch-folder-list.imap.es6
index abbd6a6a8..bba5fe2c8 100644
--- a/packages/client-sync/src/local-sync-worker/sync-tasks/fetch-folder-list.imap.es6
+++ b/packages/client-sync/src/local-sync-worker/sync-tasks/fetch-folder-list.imap.es6
@@ -3,9 +3,10 @@ const SyncTask = require('./sync-task')
 const {localizedCategoryNames} = require('../sync-utils')
 const SyncActivity = require('../../shared/sync-activity').default
 
-
 const GMAIL_ROLES_WITH_FOLDERS = ['all', 'trash', 'spam'];
 
+const assignedRolesCache = new Set();
+
 class FetchFolderListIMAP extends SyncTask {
   constructor(...args) {
     super(...args)
@@ -23,6 +24,19 @@ class FetchFolderListIMAP extends SyncTask {
     return Folder;
   }
 
+  async _roleAlreadyAssigned(role) {
+    if (assignedRolesCache.has(role)) {
+      return true
+    }
+    const Klass = this._classForMailboxWithRole(role, this._db);
+    const existing = await Klass.findAll({where: {role: role}})
+    if (existing.length > 0) {
+      this.assignedRolesCache.add(role)
+      return true
+    }
+    return false
+  }
+
   _detectRole(boxName, box) {
     return this._roleByAttr(box) || this._roleByName(boxName);
   }
@@ -95,7 +109,10 @@ class FetchFolderListIMAP extends SyncTask {
 
       let category = categories.find((cat) => cat.name === boxName);
       if (!category) {
-        const role = this._detectRole(boxName, box);
+        let role = this._detectRole(boxName, box);
+        if (await this._roleAlreadyAssigned(role)) {
+          role = null;
+        }
         const Klass = this._classForMailboxWithRole(role, this._db);
         const {accountId} = this._db
         category = Klass.build({
@@ -109,7 +126,7 @@ class FetchFolderListIMAP extends SyncTask {
         // if we update the category->role mapping to include more names, we
         // need to be able to detect newly added roles on existing categories
         const role = this._roleByName(boxName);
-        if (role) {
+        if (role && !(await this._roleAlreadyAssigned(role))) {
           category.role = role;
           await category.save();
         }