There is no single recycle bin. What windows does is, it creates a
Recycled folder in the root of every drive. Whatever you delete in a drive goes to the Recycled folder in that particular drive. Inside that folder many subfolders are created with the the names like you mentioned:
S-1-5-21-725345543-2000478354-839522115-1006 and so on...
Windows keeps track of it from a single recycle bin from the desktop. Its that simple.
If you are worried with such folders, then just hide the hidden folders and its gone...!