Depends on how Mandalorians are viewed.
For instance if you meet a 9 meter tall shark man chances are you would remember it - that being the case the next time you meet one you might mention it to them 'ah one of you, another of your kind lives nearby, friend of yours?'.
If Mandalorians are viewed as 'the ultimate warrior' then one might expect to hear about another 'ultimate warrior' fairly quickly if the other one is not being stealthy.