Multipage form redirects

Hi there,
I split a long form over two pages with redirects upon submit from form page 1 to form page 2 and from form page 2 to a thank-you page. The second redirect briefly goes to the thank-you page and then immediately jumps back to form page 2. I tried to redirect through the standard redirect option, through html code upon submit, and through JavaScript inside the submit event, but the behavior stays the same. 
Any explanations for this behavior and ideas to work around would be highly appreciated.

I found out that this strange behavior only happens when in developer mode. When I tested a published website, the problem caused by serial redirects did not occur.