If Short Name is enabled on iOS and two contacts share the same first name, how will their last name be displayed with the default setting?

When navigating to Settings/Contacts on an iOS device, an option called “Short Name” is listed; briefly, this allows a user to specify how they’d like names to be shown within apps that support this feature. If enabling this setting and keeping it at the default of “First Name Only”, assuming that a user has two people with a first name of “John” in their contacts – both having different last names, how would iOS display this? Would it simply ignore the last name entirely (as dictated by the “Short Name” setting), or are exceptions made in this case – so that, for example, the first name and first letter of a contact’s last name will be shown?