[kiwidude]

Your original question was what search would bring those two books back, to which the answer is Similar Author, Ignore Title. Yes that will bring other books back for the author combinations as well depending on how many other books they have, however the recommendation I put with this plugin as per the first post is that you use it with a search like this first to find your author duplicates, and then find your title duplicates.

In this particular case, having a title that is prefixed with series information means that a more granular match on title only cannot be made. If the differences between the titles was some kind of suffix, then it could likely be matched with a fuzzy type search or something. You asked if you would be no better off than without using the plugin - I would argue that using the plugin to identify the author duplicates and hence present a subset of your library to you in that group to visually scan is way better off than scanning without it. However as I suggested if you follow the crowd in stripping series information out such as by using Quality Check to identify them that issue goes away.

As to why not to put series information in your titles - there are certainly multiple areas of Calibre which will "break" or work less than ideally if you do. One such example is the Download Metadata function, as the download metadata plugins will do a comparison between the title of the book in Calibre with the search result from the website to verify they are the same book (unless matched by ISBN). Duplicate detection at the time you add books won't work. Numerous other plugins will also not work very well - things like the Search the Internet and as you have found Find Duplicates for a start without thinking too hard. There could well be other parts of Calibre affected by having extra long title names etc. Renumbering a series? Well that's going to involve renaming the title for you, which means a different file between the Kindle and calibre which means a mess of duplicates on your device.

It is just generally a bad idea, you are working against Calibre, not with it. The series column is specifically there for this purpose. The only reason I know of people putting series information in the titles is because they did it thinking they had to as the way to get them sorted how they like either within Calibre or when exported out. In both scenarios there are better ways to handle this. To sort within Calibre, you can do a sort on multiple columns (the View Manager plugin can help with this). To assist sorting when stored on a device, if the device uses metadata rather than filenames for sorting (like a Kindle) then use a metadata plugboard, there is a sticky in the forums for how to set it up. Do it once, then forget about it.

There are no valid reasons I have seen for not stripping series out - beyond users just not being aware of how to otherwise manage their sorting on the device. And that is to be expected by the way - I wouldn't see Calibre as the most intuitive or easy to use in that area, users will have to come hunting in the forums to figure that part out.