diff --git a/deploy/onboard-node.sh b/deploy/onboard-node.sh
index c374c2b..4ea5aa6 100644
--- a/deploy/onboard-node.sh
+++ b/deploy/onboard-node.sh
@@ -38,6 +38,11 @@ NODE_TOKEN="${NODE_TOKEN:-}"
 [[ -n "${NODE_ROLE:-}" ]] && NODE_ROLE_EXPLICIT=1 || NODE_ROLE_EXPLICIT=""
 NODE_ROLE="${NODE_ROLE:-worker}"
 NODE_IP="${NODE_IP:-}"
+# NODE_NAME pins this node's cluster identity (the heartbeat key). Default to the
+# OS hostname, but ALWAYS write it explicitly so cloned VMs that share an
+# /etc/hostname (e.g. two boxes both named "zampp1") don't collide on the same
+# cluster_nodes row — which silently hides the capture node's DeckLink devices.
+NODE_NAME="${NODE_NAME:-$(hostname)}"
 AGENT_PORT="${AGENT_PORT:-7436}"
 PROFILES="${PROFILES:-}"
 BMD_MODEL="${BMD_MODEL:-}"
@@ -200,6 +205,7 @@ info "Writing $ENV_FILE"
   echo "MAM_API_URL=$MAM_API_URL"
   echo "NODE_TOKEN=$NODE_TOKEN"
   echo "NODE_ROLE=$NODE_ROLE"
+  echo "NODE_NAME=$NODE_NAME"
   echo "NODE_IP=$NODE_IP"
   echo "AGENT_PORT=$AGENT_PORT"
   echo "HEARTBEAT_MS=30000"
diff --git a/docker-compose.worker.yml b/docker-compose.worker.yml
index 895c906..278cc07 100644
--- a/docker-compose.worker.yml
+++ b/docker-compose.worker.yml
@@ -47,6 +47,10 @@ services:
       MAM_API_URL:   ${MAM_API_URL}
       NODE_TOKEN:    ${NODE_TOKEN:-}
       NODE_ROLE:     ${NODE_ROLE:-worker}
+      # NODE_NAME pins the cluster identity (heartbeat key). Set it per-node so
+      # cloned VMs that share /etc/hostname don't collide on the same
+      # cluster_nodes row. Falls back to the OS hostname when unset.
+      NODE_NAME:     ${NODE_NAME:-}
       NODE_IP:       ${NODE_IP:-}
       AGENT_PORT:    ${AGENT_PORT:-7436}
       HEARTBEAT_MS:  ${HEARTBEAT_MS:-30000}
diff --git a/services/node-agent/index.js b/services/node-agent/index.js
index 18f5660..4453016 100644
--- a/services/node-agent/index.js
+++ b/services/node-agent/index.js
@@ -5,6 +5,16 @@ import fs   from 'fs';
 const MAM_API_URL  = (process.env.MAM_API_URL  || 'http://localhost:3000').replace(/\/$/, '');
 const NODE_TOKEN   =  process.env.NODE_TOKEN   || '';
 const NODE_ROLE    =  process.env.NODE_ROLE    || 'worker';
+// Cluster identity. The heartbeat keys cluster_nodes on hostname (ON CONFLICT
+// (hostname)), so two machines reporting the SAME os.hostname() clobber each
+// other's row — exactly what happens with cloned VMs that share /etc/hostname
+// (e.g. two boxes both named "zampp1"). The capture node's DeckLink capability
+// then lands on the wrong row and gets overwritten by the primary's cardless
+// heartbeat, so the recorder UI shows "No SDI devices auto-detected".
+// NODE_NAME (set per-node by onboard-node.sh / the node's .env) overrides
+// os.hostname() so identity is explicit and collision-proof. Falls back to the
+// OS hostname when unset, preserving existing single-host behaviour.
+const NODE_NAME    =  process.env.NODE_NAME    || os.hostname();
 const AGENT_PORT   = parseInt(process.env.AGENT_PORT   || '7436', 10);
 const HEARTBEAT_MS = parseInt(process.env.HEARTBEAT_MS || '30000', 10);
 const LIVE_DIR     = process.env.LIVE_DIR || '/mnt/NVME/MAM/wild-dragon-live';
@@ -711,11 +721,11 @@ async function heartbeat() {
   }
 
   const payload = {
-    hostname:     os.hostname(),
+    hostname:     NODE_NAME,
     ip_address,
     role:         NODE_ROLE,
     version:      VERSION,
-    api_url:      `http://${ip_address || os.hostname()}:${AGENT_PORT}`,
+    api_url:      `http://${ip_address || NODE_NAME}:${AGENT_PORT}`,
     cpu_usage,
     mem_used_mb:  Math.round((totalMem - freeMem) / 1048576),
     mem_total_mb: Math.round(totalMem / 1048576),