Ok, not exactly showering me with examples there
but you mentioned something which perhaps clicked for me.
Do you mean the situation where perhaps as the result of a metadata download pulling different series names you have something like:
Title: Book A Series: The Foo[1]
Title: Book B Series: Foo [2]
Is that what you mean? If so, then what you are asking for is not so much a duplicate search as some kind of series consolidation?
The Quality Check plugin has something related to this, with its "Check Series Gaps" functionality. However it would tell you that you are missing book 1 of the "Foo" series, and of course while strictly true that isn't really the case thanks to the series name fluctuation.
Have I hit the scenario you had in mind?