problem of displaying duplicate records after checkbox is removed

Hello.
I've encountered a problem which is I'll get duplicate records when I've selected a record which is supposed to be removed after I've clicked a button, and then this record will be written into a TextFile.
In this case, EnableViewState="true".

I've set the EnableViewState to "false".
Yes, it wont display duplicate record again BUT it wont remove or write the record into the TextFile which I've selected.

What I want is, For example:
2 records are displayed on a page.
1 of it is being selected.
When I clicked OK button, it should be removed from the page and written into the TextFile without duplicating any records.

Thanks in advance!
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