Submission error: A submission already exists with this ID, but with different XML

1. What is the problem? Be very detailed.
Hello, how are you ?
I am facing a form submission error, 2 error out of 112 received. I ask for assistance please
2. What app or server are you using and on what device and operating system? Include version numbers.
central odk : 1.2.2
odk : v2021.3.0