GIT - What happens if the same file is modified by 2 users

There is a small possibility of a merge conflict situation. When that happens, need to delete the repository and recreate it from Appvance IQ.

Changes done by a second person trying to push will be lost.

If there is no conflict, changes done by the first person will be overwritten by changes saved by the second person.

Recommended approach 

The recommended approach would be to create branches per person and merge the code to the master or the main branch.