If I use the following line:
shutil.copyfile(r\"\\\\mynetworkshare\\myfile.txt\",\"C:\\TEMP\\myfile.txt\")
everything works fine. However, what
The r used in your first code example is making the string a "raw" string. In this example, that means the string will see the backslashes and not try to use them to escape \\ to just \.
To get your second code sample working, you'd use the r on the strings, and not in the copyfile command:
source_path = r"\\mynetworkshare"
dest_path = r"C:\TEMP"
file_name = "\\myfile.txt"
shutil.copyfile(source_path + file_name, dest_path + file_name)