impdp import fails with object already exists in oracle 10g?
Looks like a serious error. What is writte in the alertlog file?
First thought is that the file is damaged.
How exactly did you drop the tablespace[s]?
how exactly did you perform the export?
how exactly did you re-create the tablespace[s]?
how exactly did you re-create the schema?
how exactly did you perform the import?
You should have dropped them using 

drop tablespace X including contents and datafiles;


This would have taken care for cleanup of the old tablespaces. I also expect that you would have gotten errors during the import. When messing with databases and tablespaces, a little dba training would be very good. For 10g start here Oracle® Database 2 Day DBA
10g Release 2 (10.2)


and yes, this is more a dba question and task than for a developer.