Macbook Pro Late 2011 13英寸双外接显示器镜像问题求助

Hey there! Let’s work through this dual-display mirroring issue together— I’ve helped folks troubleshoot similar setups before, and usually it’s a small fix that gets things working right.

• Not all Mini DisplayPort-to-dual-HDMI adapters support extended display! A lot of budget adapters only replicate the signal (aka mirroring) instead of handling separate video streams. Double-check your adapter’s specs— it needs to explicitly state "extended display support" or "multi-monitor functionality" on the packaging or product details. If it just says "dual HDMI output", it’s probably a mirror-only device, and you’ll need to swap it for one that supports true extended mode.

• Start with a full restart: Power down your MacBook and both Sanyo TVs, wait 30 seconds, then power everything back on. Temporary signal glitches are way more common than you think.
• Open System Settings > Displays. If you don’t see options for multiple monitors, hold down the Option key while clicking "Detect Displays"— this trick often forces macOS to recognize external displays that are hiding.
• Once the displays show up, go to the "Arrangement" tab. Uncheck the "Mirror Displays" box, then drag the monitor thumbnails to set their physical layout (so your cursor moves between them correctly).

• Make sure the adapter’s USB power cable is plugged into your MacBook! Many dual-output adapters need USB power to run extended display mode— if you only plugged in the Mini DisplayPort cable, it might only be able to output a mirrored signal.
• Swap out your HDMI cables or switch which TV uses which adapter port. Sometimes a faulty cable or loose port can make macOS think both displays are the same device.
• Give your MacBook’s Mini DisplayPort a quick clean with a soft brush— dust buildup can cause flaky connections that mess up display detection.

• If you’re running a newer macOS version (Ventura or later), corrupted display cache can cause issues. Reset it by opening Terminal and running this command:
  sudo killall -HUP WindowServer
  (Enter your admin password when prompted— your screen will flash briefly as the display service restarts, that’s normal.)
• Double-check your MacBook Pro’s specs to confirm it supports dual external displays. Most Mini DisplayPort-equipped models do, but it’s worth verifying just to rule out hardware limitations.

内容的提问来源于stack exchange，提问作者Galtin