"Duplicate Timestamps" Error When Importing Previously Exported CSV Data to ThingSpeak

I exported my channel feed to CSV format, deleted the channel feed data, then tried to import the CSV back into the channel without making any modification to the CSV file. I recieve the error "The file was not uploaded because it contains duplicate timestamps. See Channel Data Import for more information." I have confirmed that there is no duplicate timestamp data in the CSV. This seems to have been an issue in the past: https://www.mathworks.com/matlabcentral/answers/506094-can-t-import-csv-file-into-thingspeak

How can I upload the CSV data back into the channel?

Thanks!