How To Install Multi-pixel Using GTM
1. Add Facebook Pixel Template to Tag
After logging in to Google Tag Manager, go to Templates > Tag Templates > Search Gallery.
The template tag list will pop up on the right, find Facebook > select Facebook Pixel > Add to workspace > Add.
2. Add multiple Facebook Pixels to your page
You go to Tags > New > Tag Configuration > Facebook Pixel.
In the Facebook Pixel ID(s) box, enter your Pixel ID.
If you want more than one pixel to track this event, enter those pixels in this section, separated by commas.
In the Event Name section, select the event you want to track.
In the Triggering section, you choose the tag triggering condition.
Then you name the Tag and press Save.