Just one printer.  It prints the chef ticket with a number on it and the customer number together.  The customer number is cut almost all the way across so it tears easy. Chef ticket goes to the rail, number goes to the customer.  The chef ticket also has a time stamp on it which is nice to monitor turn times.  
We had a guy that complained about waiting over 10 minutes for his food, the ticket showed me he had been waiting four minutes.  Of course I did not share that with him but at least I knew the truth. 
 
Another option is to type their name on the order and it will print out on the chef ticket.  It takes longer to type the name but when you are giving orders out by number people can get grumpy when a later number gets served first.  We have some 1 minute sandwiches and our fried goods are done to order so they take 3 minutes.