Yes. There are pages that start with dlang.org/phobos/... and others that start with dlang.org/library/... I need to confirm but I think the "Phobos" ones are for the current library of D(ver)2 and "library" ones are for Tango, a different library that diverged from the standard one during the D1 days - something like that. I think I read that they have later sort of unified again, either that, or Tango is obsolete or less recommended. Maybe others who know more can comment.
Everything on dlang.org is fine. The phobos/ and library/ sections are two versions of the same content, generated from the same source files at the same time. The library/ stuff is the future, but not completely polished yet.
The obsolete stuff is dsource.org. Most of it does not compile anymore and has no maintainers. If you are looking for libraries to use, go to https://code.dlang.org/.
Phobos is the standard library. Tango is a D1 projects. Most of it has been ported and integrated into Phobos now. Some people still like the Tango XML library: https://github.com/SiegeLord/Tango-D2
