diff --git a/frontend/js/views/dashboard.js b/frontend/js/views/dashboard.js
index bbfb349..94b01dc 100644
--- a/frontend/js/views/dashboard.js
+++ b/frontend/js/views/dashboard.js
@@ -246,7 +246,6 @@ export function render(container) {
   };
 
   screenshotHandler = (data) => {
-    // Update all instances of this device's preview (may appear in multiple groups)
     document.querySelectorAll(`#preview-${data.device_id}`).forEach(preview => {
       const imgSrc = data.image_data || (data.url + '&token=' + localStorage.getItem('token'));
       const img = preview.querySelector('img');
@@ -286,7 +285,13 @@ async function loadDashboard() {
   if (!main) return;
 
   try {
-    const [devices, groups, playlists] = await Promise.all([api.getDevices(), api.getGroups(), api.getPlaylists()]);
+    const [rawDevices, groups, playlists] = await Promise.all([api.getDevices(), api.getGroups(), api.getPlaylists()]);
+
+    // Deduplicate devices by id — a stale reconnect race can briefly cause the same
+    // device to appear twice in the list. Last-write-wins keeps the freshest state.
+    const seen = new Map();
+    for (const d of rawDevices) seen.set(d.id, d);
+    const devices = Array.from(seen.values());
 
     // Stats
     const online = devices.filter(d => d.status === 'online').length;
@@ -339,10 +344,17 @@ async function loadDashboard() {
       return { ...g, devices: fullDevices, memberIds };
     }));
 
-    // Find ungrouped devices
-    const allGroupedIds = new Set();
-    groupsWithDevices.forEach(g => g.memberIds.forEach(id => allGroupedIds.add(id)));
-    const ungrouped = devices.filter(d => !allGroupedIds.has(d.id));
+    // Render each device exactly once: the first group it belongs to wins.
+    // memberIds is preserved for the Manage modal so multi-group membership info stays accurate.
+    const renderedIds = new Set();
+    for (const g of groupsWithDevices) {
+      g.devices = g.devices.filter(d => {
+        if (renderedIds.has(d.id)) return false;
+        renderedIds.add(d.id);
+        return true;
+      });
+    }
+    const ungrouped = devices.filter(d => !renderedIds.has(d.id));
 
     let html = '';
 
diff --git a/server/ws/deviceSocket.js b/server/ws/deviceSocket.js
index 0b1316a..7e3bb7f 100644
--- a/server/ws/deviceSocket.js
+++ b/server/ws/deviceSocket.js
@@ -118,6 +118,19 @@ module.exports = function setupDeviceSocket(io) {
   const deviceNs = io.of('/device');
   const dashboardNs = io.of('/dashboard');
 
+  // Disconnect any existing socket that is currently registered for this device_id.
+  // Called when a fresh registration comes in for the same device so the old (likely
+  // half-dead) socket can't fire its disconnect handler and clobber the new entry.
+  function evictPriorSocket(deviceId, exceptSocketId) {
+    const prior = heartbeat.getConnection(deviceId);
+    if (!prior || prior.socketId === exceptSocketId) return;
+    const oldSocket = deviceNs.sockets.get(prior.socketId);
+    if (oldSocket) {
+      console.log(`Evicting prior socket ${prior.socketId} for device ${deviceId}`);
+      try { oldSocket.disconnect(true); } catch (_) {}
+    }
+  }
+
   deviceNs.on('connection', (socket) => {
     console.log(`Device socket connected: ${socket.id}`);
     let currentDeviceId = null;
@@ -145,6 +158,7 @@ module.exports = function setupDeviceSocket(io) {
                 db.prepare('UPDATE devices SET device_token = ? WHERE id = ?').run(newToken, existing.device_id);
                 console.log(`Fingerprint match: linking reinstalled app to existing device ${existing.device_id} (new token issued)`);
                 authenticated = true;
+                evictPriorSocket(existing.device_id, socket.id);
                 db.prepare("UPDATE devices SET status = 'online', last_heartbeat = strftime('%s','now'), ip_address = ?, updated_at = strftime('%s','now') WHERE id = ?")
                   .run(getClientIp(socket), existing.device_id);
                 socket.emit('device:registered', { device_id: existing.device_id, device_token: newToken, status: 'online' });
@@ -189,6 +203,7 @@ module.exports = function setupDeviceSocket(io) {
 
           currentDeviceId = device_id;
           authenticated = true;
+          evictPriorSocket(device_id, socket.id);
           db.prepare("UPDATE devices SET status = 'online', last_heartbeat = strftime('%s','now'), ip_address = ?, updated_at = strftime('%s','now') WHERE id = ?")
             .run(getClientIp(socket), device_id);
 
@@ -384,6 +399,15 @@ module.exports = function setupDeviceSocket(io) {
 
     socket.on('disconnect', () => {
       if (currentDeviceId) {
+        // If a newer socket has already taken over this device_id, this is a stale
+        // disconnect from a replaced socket — skip the offline transition so we don't
+        // flip an actively-connected device offline or clobber the new heartbeat entry.
+        const activeConn = heartbeat.getConnection(currentDeviceId);
+        if (activeConn && activeConn.socketId !== socket.id) {
+          console.log(`Stale disconnect for ${currentDeviceId} (socket ${socket.id}); active is ${activeConn.socketId}, skipping offline`);
+          return;
+        }
+
         console.log(`Device disconnected: ${currentDeviceId}`);
         db.prepare("UPDATE devices SET status = 'offline', updated_at = strftime('%s','now') WHERE id = ?")
           .run(currentDeviceId);