Question

what will happen if you create a file with same name which already exit

Answer 1

There are two possibilities:

a)If you're moving a single file then the original file will be replaced because  two files with same name can't reside together in the same folder.

b)In case of folders however, you'll get to choose either replace the older folder or merge their contents together.

Answer 2

If there already exists a file of the same name and type you will have to rename this one or replace the old one. If the files are of different types then there is no issue