easy question about dual processors and .bat files

I have a computer with dual processor. And to take advantage of them both processors to render I make a .bat file (i´m not programmer). Let us suppose that my .blend has thousands frames, I am making bat that opens blender and render from the 1 to the 500 and other to render from the 501 to the 1000. It works well but only opens one instance of blender, it begin to render and it does not open the other.
Anyone can help me?
thnk you
This is the bat file:

blender -b ropa.blend -s 1 -e 499 -a

blender -b ropa.blend -s 500 -e 1000 -a

@Pause

Thats because your batch file is executing the first
render command and waiting for it to finish, then
executing the second.

If you change your batch file to

start blender -b ropa.blend -s 1 -e 499 -a
start blender -b ropa.blend -s 500 -e 1000 -a

the two commands will run seperatly from the batch
file (although they will open two dos windows, which
is a bit annoying, and the batch file will finish immediatly,
so if you have other things you want to do after rendering
you will have to start them by hand).

(start is a windows command that will run the
given program and arguments seperatly, among
other handy things).

thank you very much!! :smiley: :smiley:
It works fine