batman

@echo off
(for /f "delims=" %%a in (1.txt) do (
   if not defined "%%a" echo %%a&set ""%%a"=a"
))>new.txt
start new.txtCOPY

ps:去掉重复行的代码和贴子论坛实在是多，楼主为什么不搜索一下呢。。。