Deleting Duplicate Rows

I have a csv file that I need to import daily into a SQL Server 2005 table. Much of the table contents could just be overwritten with the new csv file, however there are a set of Rows within the table that need to be appended to , rather than overwritten. 

There is no Primary Key in the csv file that can be used.  

I'm not sure this is the best approach, but what I have been trying to do, is append the entire csv file to the existing table, and then go back and delete the duplicates.

When I run the Delete, it does delete the majority of the records, but leaves a couple hundred behind. The number left behind varies with each run, can't seem to identify a pattern here. Running the Delete a second time does clean up the rows left behind in the first execution of the Delete, and gives the result I want.

Any thoughts as to why this needs to be run twice? Or is a better approach available?

Here is my code -

SELECT [Pkg ID], [Elm (s)], [Type Name (s)], [End Exec Date], [End Exec Time], dupcount=count(*)

INTO temppkgactions

FROM pkgactions

GROUP BY [Pkg ID], [Elm (s)], [Type Name (s)], [End Exec Date], [End Exec Time]HAVING count(*) > 1

 

DELETE TOP (SELECT COUNT(*) -1 FROM dbo.temppkgactions WHERE dupcount > 1 )

FROM dbo.pkgactions

DROP TABLE temppkgactions

 

Thanks