In Excel, duplicate data can be a problem that makes spreadsheets less useful. To find duplicates, users can use the "Remove Duplicates" feature or highlight duplicate content using conditional formatting. The "Remove Duplicates" feature allows users to automatically remove duplicate rows in one fell swoop by selecting specific columns and clicking OK. Alternatively, users can use the UNIQUE function to return unique values from a list or range without permanently deleting data. To automate tasks related to Excel, such as removing duplicate data, users can connect their spreadsheet with other apps using Zapier, which allows for automation of spreadsheet-related tasks and removal of human error.