How do I stop Adobe merging my documents when printing multiple copies?

Can anyone help?

Every time I try and print several 2-sided copies of a multi-paged document, if it is an odd number of pages - it starts the next copy on the back of the previous copy.

So if I've got a document 3 pages long, it would normally print  1&2 back to back and then 3& nothing page back to back.

ALL other packages I use will do this, but not Acrobat.

Acrobat seems to not want to waste paper! and instead decides to start the next copy without the break:

e.g.  Acrobat will print  1&2 back to back and 3&1(of next copy) then 2&3 etc. So it's not even that I can then go back and reprint the messed up second page of everything, it completely stuffs up my printing.

Is there a setting I'm just not aware of? It's seems crazy that ALL other packages know not to do this, but Acrobat thinks this is ok!

It is driving me bonkers - not to say wasting lots of paper and ink.

thanks