You can try this (or maybe you already have)...open the report in Print Preview and then click on Page Setup. Under the Page tab make sure that you have your paper size selected and then you can also set the default printer to your Epson.
I did this for a report with non standard paper size printing to a dot matrix and it works fine.
But I did this all. The printer's default paper size is my saved from name which I set up from Server Property. Even before printing I check the paper size. But it still need to roll back once printed invoice.
I don't know if I understand why the printer would have to be rolled back... is it doing a form feed after getting the half page height printed and so you want to roll it back to where the second invoice should go: the bottom half of page 1?
If so, you need to turn off your printer's "form feed after job completion" feature, whatever it is called in that model.