You can query a person who called your second number or whom you called with your second number through the call log. They will not receive a notification. Similarly, when you go to the profile detail via incoming or outgoing SMS, they will not receive a query notification.
However, when you make queries from the search field or go to the profile in other ways such as selecting from the contacts, they will receive a query notification. This is because your main number is used in search and contacts feature. Your second number is not used for these processes.
If you do not want the other party to be notified while you are obtaining information about the person who reached your secondary number, you should query only by clicking on the incoming/outgoing call record from your secondary number or on the relevant person in the details page of the incoming SMS.
If you make the query in any other way, the other party will also be able to view your main account information, which is your Getcontact account.