Uninvited Supplier Contact can view/revise responses of Invited Supplier Contact, how to restrict?

Summary:

A negotiation has been published to Supplier Bidder A (invited supplier contact) of Company XYZ but there is Supplier Bidder B (not invited supplier contact) from the same company. Both of these supplier contacts has- Supplier Bidder roles added in their user accounts.

Issue: Supplier Bidder B logged in and the system allowed this user to create/revise the response that Supplier Bidder A has submitted in the View Active Negotiation. It seems that this is the expected behavior because of the roles assigned to both Supplier Bidders but we tried to publish the negotiation from the Supplier Site which is not linked to Supplier Bidder B but still the user was able to create/revise the response.