Because each monitor is independent, you can use any mix of VGA, DVI, and HDMI cables simultaneously.
Is it possible to use HDMI and VGA at the same time?
It is physically possible to attach a VGA and HDMI connector at the same time. Most likely yes.
How do I display HDMI and VGA at the same time?
HDMI->VGA – Input is HDMI and Output is VGA (Audio is lost). If your display supports HDMI and your RPi provides HDMI output, then you can directly connect RPi HDMI port to HDMI port of monitor. If your display supports only VGA but RPi is HDMI, then you need HDMI to VGA converter + (VGA to VGA cable).
Can I use HDMI and DisplayPort at the same time?
You can freely combine HDMI, DisplayPort, and DVI. One monitor can be HDMI, the other DisplayPort and so forth. Video connections are one thing, but remember your extra monitors won’t run themselves.
Can I use VGA and DisplayPort at the same time?
In a word: Yes. You can use DisplayPort and VGA at the same time to connect two monitors to your PC. However, you should make sure that your motherboard is up for that type of work.