Test data is very important in manual testing as well as in automation testing. But if the test data changes in manual testing then it is not a big issue when compared to automation testing. As in the manual testing the tester can change/create the data as he is aware that the data changes and he will have enough application knowledge. But when it comes to the automation, the tool can not have this kind of knowledge or information. To avoid these kind of issues we can use some third party APIs to generate random unique test data or fake data.