Em vez de fc use findstr com as opções:
/V Prints only lines that do not contain a match.
/I Specifies that the search is not to be case-sensitive.
/B Matches pattern if at the beginning of a line.
/E Matches pattern if at the end of a line.
/G:file Gets search strings from the specified file(/ stands for console).
Você pode reunir as opções com apenas um /
> findstr /VIBELG:mount.txt <mount2.txt
Logo
ITCMDSecondLogo