Why google drive create so many conflict files

I have a window system and a mac. When I create a file (e.g. a.cpp) in my window (with vim), google drive create a lots of files like a (1).cpp , a (2).cpp ...

Some of them are delete by google drive after it create them. Some are not.

Why google drive generate so many files?

Also a.cpp is not the same as a.cpp in windows. a (2).cpp in mac is the same as a.cpp in windows in some cases.

Why the same files have different content?

When I check the access right of files, it should something like -rw------ .................. a.cpp However when I create a file b.cpp in mac it is -rw-r--r- .................. b.cpp

Is it because of the accessing privilege problem?