Display when multiple users access the same record
Zendesk does this brilliantly. When more than one user is accessing the same customer record, or opportunity/case at the same time it is clearly displayed in order to reduce multiple edit issues.
Capsule does allow for two users to add notes to a contact record at the same time and that is valid. In terms of editing contact details - if they are being edited and a second user tries to edit them, person #2 will get an error saying the contact is already updated. So you are protected from simultaneous edits even though the contact isn't locked down as a support ticket might be.