Discount Coupon - Automatic Generation vs limiting uses per customer

Hi from New Zealand,
I have set up for a 20% coupon to automatically be sent to new registrations that can be used twice. Instructions say to leave coupon number field blank if I want ZenCart to automatically generate a new number for each customer - which I did.
But upon pressing "Preview" the system automatically inserts a number.
Shouldn't it issue a different number for each customer? Otherwise only the first customer gets any benefit.
Alternatively, is the only way to do this to limit the number of uses per customer instead of per coupon?
Thansk for all your help.
Dave

There are two settings ...

Uses per Coupon
Uses per Customer

The same code can be used, it is tracked for matching the limits set ...

So if you set blank the Uses per Coupon and set 2 for the Uses per Customer this should work for you ...