Creating tickets

The next functionality that needs to be implemented is creating tickets for a certain event. Today I've been working on that functionality. It works like this: the user inserts both first and last ticket number, and tickets will be created automatically for that range. This is already functioning. Nevertheless, I have found that if an user sends a range that includes numbers of tickets already created, those tickets will lose their previous information. To solve this problem, I'm thinking on maybe warn users about that issue, and ask them if they would like to keep the old values, erase them, or insert a new range of ticket numbers.