You can run 2 monitors off 1 Mini DisplayPort using a feature called Multi-Stream Transport (MST), but there are some conditions and limitations:

1. Check for MST Support

Your graphics card or device must support MST. Most modern GPUs from AMD, NVIDIA, and Intel with Mini DisplayPort or DisplayPort outputs support this feature.

2. Use an MST Hub or Daisy Chaining

MST Hub: A Mini DisplayPort MST hub splits the signal into multiple outputs, such as HDMI or DisplayPort, allowing you to connect two monitors.

Daisy Chaining: If your first monitor supports DisplayPort Daisy Chaining, you can connect the second monitor to the first monitor using a DisplayPort cable. This requires the monitors to support DP 1.2 or higher.

3. Monitor Compatibility

Both monitors must support the resolution and refresh rate intended. The combined bandwidth for both monitors must not exceed what Mini DisplayPort can deliver. For example:

a. Mini DisplayPort 1.2 supports up to 17.28 Gbps, enough for two 1080p monitors at 60 Hz or a single 4K monitor at 60 Hz.

b. Mini DisplayPort 1.4 supports higher bandwidth, enabling even two 4K monitors depending on settings.

4. Configuration

After connecting the monitors, you'll need to configure the display settings in your operating system (Windows, macOS, or Linux) to arrange and extend the displays.

If MST isn’t supported, you can only mirror the displays or use a hardware-based splitter, which also duplicates the image rather than extending it.