Welcome to the forum.
Suggestions to try courtesy of co-pilot. Hope one works for you.
1. Unplug HDMI → reboot → plug HDMI back in → set both displays to the same resolution + refresh rate → try Duplicate again.
2. Before selecting Duplicate:
- Right-click desktop → Display settings
- Select each display → Advanced display settings
- Set both to: 1920×1080 @ 60 Hz (the most universally supported mode)
Then try Duplicate again.
3. If one display is 4K and the other is 1080p, Windows sometimes refuses to clone until you manually downscale the 4K display first.
Then try
Duplicate again.
4. Depending on your GPU:
NVIDIA
- Open NVIDIA Control Panel
- Go to Set up multiple displays
- Try enabling Clone there instead of Windows Settings.
AMD
- Open AMD Software
- Go to Display → Eyefinity / Clone
Intel
- Open Intel Graphics Command Center
- Go to Display → Multiple Displays → Clone
Sometimes the GPU driver handles cloning better than Windows.
5. Update or reinstall display drivers
6. From command prompt as admin type:
displayswitch.exe /clone
If it errors or does nothing, Windows is failing the clone negotiation.
7. You can also reset display data:
- disconnect HDMI
- Shut down PC completely
- Unplug power from monitor/TV for 30 seconds
- Reconnect everything
- Try Duplicate again
This forces a fresh EDID handshake.
Symptoms of EDID failure:
- Monitor shows “No signal” when switching to Duplicate
- Windows flashes and returns to Extend mode
- Resolution options disappear
Fixes:
- Try a different HDMI cable
- Try a shorter cable
- Remove HDMI splitters, adapters, docks
- Update monitor firmware (if available)
TVs often cause duplicate-mode issues because:
- They report unusual refresh rates (59.94 Hz)
- They use overscan modes
- They sometimes only support certain PC resolutions
Try: Set TV to
PC mode or
Game mode
- Disable overscan (“Just Scan”, “1:1”, “Full Pixel”)
- Force 1080p @ 60 Hz