I think that the first experts is for TEMPORARY TABLESPACE, and the second experts is for PERMANENT TABLESPACE which is specified as default temporary tablespace to a certain user.

This is another experts: "a single sort allocates its own temporary segment in the temporary tablespace of the user issuing the statement and then returns the extents to the tablespace. Multiple sorts, however, can use the segments in a temporary tablespace designated exclusively for sorts. These sort segments are allocated only once for the instance, and they are not returned after the sort but remain available for other multiple sorts."