Output to multiple files with imposition

I'm trying to break up an imposed file in several sections, and maintain the number sequence in the imposition. 20 up, 1000 total in the sample, stack 50. Works fine when not imposing. I have also tried infinite stack. Usually I get the whole file in one document.

What numbers would I put in the "output to multiple files" and "different number of records in first file" in the sample I've attached, to get 2 equal documents of 50 pages each, maintaining the number sequence?

batch test.zip

In your imposition set the stack count to 25. And in your compose settings set the output to 500 records per file (uncheck Different number of records in first file).