I am creating a case in which there's a Dropdown in which I can see the contacts and accounts list. 
If i am selecting any of the contact and saving the form. its working fine like i can see the my .xls files and other documents in the documents tab. (Perfect case)

but if I am selecting any of the account from that Dropdown , then after saving the case,I am seeing my contacts in documents tab :(
stucked .need help