Visitor multiple form submits

How can we setup certain forms to only require our website visitors to submit a form ONLY if they haven't completed a certain form?  Does that makes sense?

IE. A Website visitor goes to download a flyer, and is required to submit a form before viewing.  Then he wants to see a Case Study, which usually requires visitors to complete a form before viewing, but it does not require him to complete a second form.  We still want to capture that the visitor viewed that literature (blind form?), but we don't want him to have to complete a new form for each literature they want to see.