The full stop doesn't count. If you're successfully using 'first.last', then theirs is not 'firstlast', that is also yours, as you said yourself. Theirs is pro

The full stop doesn't count. If you're successfully using 'first.last', then theirs is not 'firstlast', that is also yours, as you said yourself. Theirs is probably 'firstlaast' or something - i.e. some typo unrelated to their decision not to separate by '.'.