@echo off
setlocal enabledelayedexpansion
for /f "tokens=*" %%_ in ('type "file.txt"') do (
	set "record=%%_"
	call :output
)
 
 
DeL /f /q file.txt
REn final.txt file.txt
exit
 
:output
if not defined prev_rec goto:write
if "%record%" EQU "%prev_rec%" goto:EOF
 
:write
echo !record! >> final.txt
set "prev_rec=%record%"
goto:eof