When I upload multiple files via Firefoxdriver it dose not works

and my code snippet shows below:

#upload file
file_path=r"E:\python project\Selenium\upload folder\Chrysanthemum.jpg"
file_path1=r"E:\python project\Selenium\upload folder\Sleep Away.mp3"
pathes='"'+file_path+'"'+" "+'"'+file_path1+'"'
file_input.send_keys(pathes) #file_input is input file element


Note: if upload single file it works.(for example: file_input.send_keys(file_path))

Meanwhile, I run above codes via InternetExploredriver it works.
For chromedriver, should be coding that: 
file_input.send_keys(file_path,"\n",file_path1)

For multiple files, how to do for Firefoxdriver?  which string should be use to separated?
Thanks!