If it is correct, it will remain in your history for 7 years, it should not show as open though.
If lender A accepted a settlement for a reduced amount, but also referred you to collector B in error, and you now have a negative mark from both A and B, then you should contact lender A and all three credit bureaus to appeal. While the appeal is pending, you have the right to place a 300 word statement of explanation in your file, although the statement won't affect your score. Don't forget to follow up with all 3 credit reports, Turbo® only shows you one. You can get all 3 reports at www.annualcreditreport.com.
