Removing repeated section of string
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I'm having trouble with data manipulation in a txt file. My file currently looks like this:



        HG02239 -23.42333333
        NA06985NA06985  -20.125
        NA06991NA06991  -20.92

This shows some of my tab-delimited data. Half the entries are in the correct seven-characters (letterletternumbernumbernumbernumbernumber) format, but some are doubled up. I want to go into the second column (first column is empty for a reason!) and remove the repeats in the string so it would read 


        HG02239 -23.42333333
        NA06985  -20.125
        NA06991  -20.92

I can't work out how to do this with sed/awk on a per column basis. I feel like I should be able to write a regex, but because the data is a repeat, I don't want to lose the first half of the string; and I can't work out how to cut on a specific column, or I would just delete the 7th character. Any help much appreciated!
