Whenever I select the PHB as the only source I want to filter on in the Spells list, the Basic Rules versions of spells are always included as well, even when I don't select them as a filtering source. Try the below link, and then search for Tiny Hut, for instance. You'll get both the PHB version and the Basic Rules version, even though Basic Rules is not selected as a filter. If I only select Xanathar's as a filter, Tiny Hut doesn't appear, so it has something to do with how the PHB is handled.
Likewise for any other searches, such as for Monsters, and items, if that's an issue with those lists.
I understand that there is content in common between the two publications (Basic Rules & Player's Handbook), except that in my example of the spells "Leomund's Tiny Hut", and "Tiny Hut", if you examine them, they aren't tagged as belonging to both BR & PHB. Look up Tiny Hut, then view each spell. Open them in two tabs on your browser, then click back and forth between the tabs. You'll find a number of differences, including an extra vertical space after the first paragraph of the spell's text for Leomund's Tiny Hut, different sources cited at the bottom right, and different "Available For" class lists.
Now use the advanced filters and select Basic Rules as the only Source. Search for Tiny Hut, and you ONLY get Tiny Hut, not Leomund's Tiny Hut. Now go back, delete Basic Rules, add in Player's Handbook (so that it's the only "Source" entry in that box), and search Tiny Hut... you'll get both entries.
This isn't a case of them linking up two different titles to the same file content... they're separate files entirely, as far as I can tell.
So when I filter on the Player's Handbook and search for "Tiny Hut", or "Mansion", there's no reason I should be seeing entries from the Basic Rules AND for the Player's Handbook when I'm filtering on JUST the PHB. It's understandable if I'm not filtering on any sources, but when I AM filtering that way, then only that source's entries should appear.
Whenever I select the PHB as the only source I want to filter on in the Spells list, the Basic Rules versions of spells are always included as well, even when I don't select them as a filtering source. Try the below link, and then search for Tiny Hut, for instance. You'll get both the PHB version and the Basic Rules version, even though Basic Rules is not selected as a filter. If I only select Xanathar's as a filter, Tiny Hut doesn't appear, so it has something to do with how the PHB is handled.
Likewise for any other searches, such as for Monsters, and items, if that's an issue with those lists.
https://www.dndbeyond.com/spells?filter-class=0&filter-search=&filter-verbal=&filter-somatic=&filter-material=&filter-concentration=&filter-ritual=&filter-sub-class=&filter-source=2
Basic rules are taken from and include certain content from PHB and DMG.
So if you filter for content in PHB, the content from the basic rules that are also included in PHB will be displayed.
Currently there is not way to exclude content in searches (i.e. PHB excluding basic or sorcerer spells excluding wizard spells).
Hopefully they eventually catch up to 1998 Google in terms of search and filter syntax.
I understand that there is content in common between the two publications (Basic Rules & Player's Handbook), except that in my example of the spells "Leomund's Tiny Hut", and "Tiny Hut", if you examine them, they aren't tagged as belonging to both BR & PHB. Look up Tiny Hut, then view each spell. Open them in two tabs on your browser, then click back and forth between the tabs. You'll find a number of differences, including an extra vertical space after the first paragraph of the spell's text for Leomund's Tiny Hut, different sources cited at the bottom right, and different "Available For" class lists.
Now use the advanced filters and select Basic Rules as the only Source. Search for Tiny Hut, and you ONLY get Tiny Hut, not Leomund's Tiny Hut. Now go back, delete Basic Rules, add in Player's Handbook (so that it's the only "Source" entry in that box), and search Tiny Hut... you'll get both entries.
This isn't a case of them linking up two different titles to the same file content... they're separate files entirely, as far as I can tell.
So when I filter on the Player's Handbook and search for "Tiny Hut", or "Mansion", there's no reason I should be seeing entries from the Basic Rules AND for the Player's Handbook when I'm filtering on JUST the PHB. It's understandable if I'm not filtering on any sources, but when I AM filtering that way, then only that source's entries should appear.