there is many circumstances:
- you may be loading from files with * (asterix)
- you could have added more files to source folder
- you may not be dropping table somewhere
- you may want to force concatenate (rather than autoconcatenate)
- you may have copied script in 2 places.
Without looking at your script it is difficult to say.
On top of that I hope you have used script editor (not datamodeler in qliksense) to build your script ,because then there should be some logic applied on script.
If you used datamodeler - autogenerated script may not work the way you think it should.
Qlik at the end is not as easy as it seems and you still need to know what you are doing in your script.
I suggest you attach your application so we can have a look at script to help you with this.
If you do not specify a name for the table, QV will pick a name based on the source file name or source table. If you load multiple files with the same name (say multiple sheets from a single spreadsheet / multiple loads from a database table or function with different filters / etc), then QV will concatenate the loads if the field list is identical, but will add a new table with a -1 extension if the field lists differ.