eForm one submit for 2 input)

Hi!

I have a form on the main page, which contains two fields, one button and the submit. If the user enters data into the first box (do not fill the second), then when you click on the submit button to be discharged to a page with a form in which this field has already been filled and the need to fill another field (field1, field2). If the user enters data in the second box (do not fill the first), then when you click on the submit button to be discharged to a page with a form in which this field has already been filled and the need to fill another field (field3, field4). If the user enters the data into both fields on the main - should show an error. How to do it?

not that simple i am afraid without js code

I tried getting something similar done too without luck so far.
Hope you can find a solution for this issue...