Hi,
HikaShop doesn't has anything related to the FaceBook pixel in it so I don't see how it could be something in HikaShop.
You said that
fb pixel event fires twice at InitiateCheckout
.
So a simple way to check on whether the issue is in the plugin from
extensions.joomla.org/extension/extensio...meta-pixel-tracking/
is to disable it. If, after that, you get 0 fb pixel event fires at initiateCheckout, and if you reenable it, you get two, it can only mean that both event fires comes from the plugin.
That's the first thing I would try. If it comes from the plugin, then the developer has to look into it.
And if you still get 1 event fire after the plugin is disabled, it means that you indeed have something else triggering the event fire on your website.