Код:
@Echo Off &Cls
>nul Chcp 1251
Set "BoxIn=Z:\Box_In"
rem Set "BoxIn=%~dp0"
Pushd "%BoxIn%"||(Echo Folder "%BoxIn%\" not found &Pause &Exit /B 2)
For /F "usebackq tokens=1* delims=_" %%f In (`2^>nul Dir /B /A:-D /O:D *_*.*`) Do Call :MyRen "%%f" "%%g"
Popd
Pause
Exit /B
:MyRen
Set /A i=1
Set "Suff="
:Begin
If Not Exist "%~n2%Suff%%~x2" (Ren "%~1_%~2" "%~n2%Suff%%~x2" &Exit /B)
Set /A i+=1
Set "Suff=(%i%)"
GoTo :Begin
Exit /B
