If you have the tags on the page, there's no way for JFBConnect to automatically ignore them. That's not a feature we've every considered and likely wouldn't implement.
With that said though, I'm not sure where your 404 page is coming from, but the code itself should be passed to your template. You *should* be able to do something like:
<?php if ($this->error->getcode() != '404') { ?>
{SCOpenGraph ...}
<?php } ?>Add all the tags you want to display when the response code is *not* 404. That's untested, and your template may behave differently depending on what's generating the 404, how the template handles it, and if you have some special 404 component (which may need it's own work). The code from above came from the following Joomla docs:
docs.joomla.org/Custom_error_pages
I hope that helps,
Alex
exclude 1 page from tags
