A short time ago I ran across a couple of bugs with the same title reported by the same Launchpad user something like:
package xyz failed to install/upgrade: subprocess post-installation script returned error exit status 139
Upon further investigation I discovered that those two bugs were duplicates but it made me wonder how many other Launchpad users had reported the same bug more than once.
I figured that the easiest way to query this information would be to use the Ultimate Debian Database, which also helpfully contains Ubuntu bug information. Using my local copy, I queried for Ubuntu bugs with the same title and reported by the same user about the same source package. The vast majority of these were package installation failures, some of which actually had consecutive bug numbers and others where the user just kept trying to upgrade over time without resolving the original issue.
I didn’t keep great stats but the quantity of apport-package bugs decreased by at least 175 when I got through marking duplicates.