There ought to be a widely accepted rule that bid packages are sealed until they are presented to the person or committee who will make the final decision about which bid to accept. Why? It's the old brother-in-law problem -- more than one bid package has been accepted so that an insider can open it and modify a competing bid for a friend or family member so it is more competitive.
It is in the best interest of an organization to have neutral parties review and accept bids. Having an insider modifying one bid to make it more competitive -- and possibly receive a kickback -- is a terrible abuse of authority.