Content tracking does currently replace the link in the a.href when clicking on it (when the link is supposed to be tracked as an interaction). This means we will first load eg piwik.php?redirect_url=... which then goes to the actual redirect_url. This redirect will track the interaction happened.

However, when there are 2 trackers, the first tracker will replace the actual target URL with piwik.php?redirect_url=... and the second tracker will track the link like this as an outlink:

Ideally, these redirect_urls can be disabled optionally see #6265, and ideally, when using multiple trackers, we disable them automatically.

The result is for example 0 interactions in the second Piwik, and the interactions are shown in the first piwik.