We only report the first email open on the primary ticket recipient. During testing, we found that recipients open their email or scroll through their inbox multiple times triggering multiple pixel fires. This would cause the pixel to fire multiple times generating multiple private comment updates on a ticket. We found this would clutter up the ticket and presently report only the first-pixel fire and read receipt.
We will be adding the ability to see how many times an email was opened and from which IP addresses in a future release.