You can run dual monitors with one HDMI port by using an adapter or an HDMI splitter.
How do I use two monitors with one HDMI port?
Sometimes you have only one HDMI port on your computer (typically on a laptop), but need two ports so that you can connect 2 external monitors. In this case: You can use a ‘switch splitter’ or ‘display splitter’ to have two HDMI ports.
Can I split a single HDMI to two monitors?
If you have one HDMI port on your game console, laptop, and cable box, you can still connect two or more monitors. You can use an HDMI splitter, HDMI adapter, or HDMI switch. An HDMI splitter will help you replicate the contents of your source devices on your two monitors.