Вместо fc используйте findstr с параметрами:
/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).
Вы можете собрать варианты только с одним /
> findstr /VIBELG:mount.txt <mount2.txt Logo ITCMDSecondLogo