Simple scenario
[ClientTable]: ClientId, ClientName, Phone, Age
[CityTable]: CityID, CityName, Country
[ClientCityTable]: ClientCityID, ClientID, CityID
Client
From the result, it really does not matter. Both ways are correct.
Advantages of the second (only one insertonsubmit)
Advantage of the first one
As you already found out, the result is the same.