or, use single quotes. You are not doing any interpolation (variable and special character substitution) within the system command, so there is no need to use double-quotes around the outside. Even if you were you could use qq:

system(qq(if not exist "%ALLUSERSPROFILE%\\desktop\\gast_2005.exe" cop
+y \\\\server\\groups\\support\\gast_2005.exe "%ALLUSERSPROFILE%\\desk
+top"))
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