Multiple Keys in threads

Question

For my program, when a client joins a MQ that was created by a server, the server starts a thread and in that thread will create a private MQ that only one specific client will have the key to.

When I create a key, since it will be one of many, does it have to have a special name? Or can I use the same one when calling ftok()?

example code:

void *thread_function(void *arg){
        key_t keyT;
    int temp;
    temp = i;
    struct my_msgbuf bufT;
    keyT=ftok("server.c", 'B'); //create key for client[temp]
    if ((client[temp].mqID=msgget(keyT, 0666 | IPC_CREAT))==-1){ //private mq for client[temp]
        perror("msgget");
    }
}

Or will have I have to make a array of key_t's, a different key for each thread?

And does keyT=ftok("server.c", 'B'); create the same key anytime you use it?