There is a simpler way to 'coalesce' a temporary type tablespace

First switch the tablespace back to permenant
Code:
alter tablespace xxx permanent;
Then coalesce the tablespace
Code:
alter tablespace xxx coalesce;
Lastly switch the tablespace back to temporary
Code:
alter tablespace xxx temporary;
Using this method you do not have to create any additional datafiles or drop any.

Regards