In addition to Affidavit of support, is there any other document i might need to fill out to invite my parents to the US of A.
What past experice does anybody have in terms of this application?

Sincerely appreciated,
Dilbert, the hardworking employee.

I am just bumping your thread but your question is very vague, what is your status, what kind of affidavit are you talking about, what do your parents do. Answer depends on so many variables.

Affidavit of Support, Form I-130 , published by the USCIS. 
I am citizen of the US. I do not have any reason for their visit other than bhetghat. I am getting a employment verification from my employer. As for my mom, she is 60 years old and stay home grandmom.

Is it OK to turn in two I-130 from two different individuals for same person's application?

http://www.path2usa.com/visitor-visa-guide/documents-for-sponsor
All information you need and templates are there like letters and what you need to submit to invite as a sponsor.