Dear Rohit
In standard system, there is no check which will restrict posting of documents other than Vendor invoice for document type "KR" i.e. even with the settings as mentioned by you, the system will allow posting of documents which are not in the nature of vendor invoice like vendor transfer and even a document consisting of GL accounts in both the line items.
If your client specifically need such a restriction, you will have to go for validation at the time of Posting of document with ABAP codes.
Thanks & regards
Nitesh