Safari renames bookmarks in the Favorites folder

From time to time Safari decides to rename some my bookmarks. I've only noticed it in the Favorites folder. For example, just now I noticed that "Mediate" had once been again renamed to "Mediaite.com | Media & Politics News | TV, Print, Online". It appears to be picking up a corporate title from someplace and dropping it into the bookmarks bar, but when it does it to several of them things begin get crowded. This has been going on for a number of months, so it doesn't seem to be related to whatever version of the software I'm running, which is usually the most current. I go in, edit the titles back what I want, and a couple of days later the longer names start to show up again.