An operating method for a controller includes: receiving a target command; detecting a first command from a first command queue, the first command having a same logical address as the target command; queuing the target command in the first command queue when the first command is not detected from the first command queue; detecting, when the first command queue is full of commands, a second command from a second command queue, the second command having the same logical address as the target command; and queuing the target command in the second command queue, when the second command is not detected from the second command queue.