@Joanna - requests are free, of course there are no guarantees of being implemented
So what you are asking for is really a fuzzy match (like Find Duplicates does) but applied to the Publisher field rather than the Title/Author. I would put this into exactly the same category as another request that has come up previously, where people have asked for something similar for matching series names.
Unfortunately that category is currently labelled as the "too hard" basket
. Not massively technically difficult to implement the searching bit, the hard part is what to do with the results. In both cases producing a report (like series gaps does) would be easiest, but that might prove not particularly user friendly and rather painful to work through in terms of typing in searches to bring the books on screen for each group of results (or a click and scroll fest in the tag browser).
Now if people come up with a clever UI idea for how to work with the results (or are prepared to accept a log report) then maybe I can be talked or bribed into adding it... until then it is in that basket I'm afraid.