correct me if im wrong!!!!

Got to McDonald's in parow centre where i figured there are two queues. I obviously went to the empty line. As the till operator finished to assist the next customer she calls a lady in the next line but I was in front of her till.. I was then confused and asked if there is 1 or 2 queues as i did not understand why she was serving a customer that's in the other queue. The lady behind the till had the audacity to tell me there are two queues but the other customer was first!!! I would like to know since when do u call a customer that's not in your queue if there is a customer in your queue. it was very upsetting!!!