diff --git a/www/common/mergeDrive.js b/www/common/mergeDrive.js
index 396798d24..9247656e1 100644
--- a/www/common/mergeDrive.js
+++ b/www/common/mergeDrive.js
@@ -65,7 +65,9 @@ define([
                     if (!proxy.FS_hashes || !Array.isArray(proxy.FS_hashes)) {
                         proxy.FS_hashes = [];
                     }
-                    proxy.FS_hashes.push(fsHash);
+                    if (proxy.FS_hashes.indexOf(fsHash) === -1) {
+                        proxy.FS_hashes.push(fsHash);
+                    }
                     if (typeof(cb) === "function") {
                         Realtime.whenRealtimeSyncs(proxyData.realtime, cb);
                     }
diff --git a/www/common/migrate-user-object.js b/www/common/migrate-user-object.js
index 2f1ea5e88..faef141a0 100644
--- a/www/common/migrate-user-object.js
+++ b/www/common/migrate-user-object.js
@@ -176,6 +176,16 @@ define([
             if (version < 7) {
                 addRoHref();
             }
+        }).nThen(function () {
+            // Migration 8: remove duplicate entries in proxy.FS_hashes (list of migrated anon drives)
+            var fixDuplicate = function () {
+                userObject.FS_hashes = Util.deduplicateString(userObject.FS_hashes);
+            };
+            if (version < 8) {
+                fixDuplicate();
+                Feedback.send('Migrate-8', true);
+                userObject.version = version = 8;
+            }
         /*}).nThen(function (waitFor) {
             // Test progress bar in the loading screen
             var i = 0;