Excess mole of HCI is added to NaOH. Why is this procedure used rather than adding a 1:1 mole ratio?

Without any context or information about what you are doing it is impossible to say. But I can only surmise that you want to neutralise all the NaOH and have a final solution containing NaCl and HCl. Why you should want to do this I have no idea
If you want a definite answer then submit the complete original question or procedure - you will then get a satisfactory answer.

You are the pig