I’m not an expert at this, but I believe different criteria params do a logical ‘AND’. If they are a list, or the same criteria it is an implicit ‘OR’. I believe what’s happening here is that these two criteria are expected to be used together and so being treated as an ‘OR’. See:
https://forum.inaturalist.org/t/how-to-use-inaturalists-search-urls-wiki-part-2-of-2/18792
You may want to try using the exclusion criteria ( &without_term_id=) to eliminate the ones you don’t want. Logically that should work with an ‘OR’.
Lots more info on using URL params here:
https://forum.inaturalist.org/t/how-to-use-inaturalists-search-urls-wiki-part-1-of-2