Are you sure they're search engines? Please post a list of the names here so we can see what's happening. Even better if you could take a screen shot and upload it here.

Download the Mozilla Search Reset {web link} This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

oh I'm so sorry, I forgot that I've installed Add to Search Bar 2.5 add-on on my browser and this is not ff's original feature! So either I have to contact the developer or find another similar add-on.

I also use Add To Search Bar. And I have about 30 engines.

Try the search reset in my last post.

delete the search.json file and possible search-metadata.json and search.sqlite files in the Firefox profile folder to reset the search engines to the default.