Python file saved in Mac and opened in Windows adds empty blank line

Hi all, 

I don't know if my problem is an actual feature of PyCharm or not, but it is very annoying.

I have created a few python scripts using a PyCharm in a Windows pc. 

After editing the files in PyCharm using a Mac computer and going back to the PyCharm in Windows, a blank line has been added between every line.

Does anyone know why?

Thanks