@echo off

setlocal EnableDelayedExpansion

for %%i in ("%cd%\first\*.*") do (
    set uniq=0
    for /f %%x in ('crc32 %%i -nf') do (
        set one=%%x
        call:find_two "%%i"
    )
    if !uniq!==1 (
        echo %%i >>result.txt
    )
    :next
)
exit

:find_two
for %%j in ("%cd%\second\*.*") do (
    for /f %%x in ('crc32 %%j -nf') do (
        set two=%%x
        call:compare "%%j"
    )
)
goto:eof

:compare
if !one!==!two! (
    goto next
) else (
    set uniq=1
)
goto:eof