Sometimes, rarely there might occur a situation where deleted items from your credit report reappear even after the dispute resolution process has been completed. This may happen because of few reasons. 

The dispute resolution process allows for information to be removed from a credit report. The disputed item is removed from your report if the creditor cannot verify it or doesn't respond to the credit bureau’s request for an inquiry within the given time.

However, the credit bureau does not necessarily block an item from ever being re-reported within the 30-day limit, if it is initially removed. Imagine, if a creditor fails to respond within its given time phase of 30 days but then responds after that, confirming that the disputed information is correct. This way the item can be reinserted on the credit report.     

The information will be removed by the credit bureaus if the creditors send no update. But it can be reinserted if the creditor re-reports to the credit bureau later as part of their normal credit reporting updates.

Additional Reading: Does Your Credit Score Go Up When Enquiries Are Removed From Your Credit Report