Abstract: A dual screen displaying device for displaying two NTSC video signals on the left and right sides of a monitor is disclosed. The displaying device comprises two tuners for receiving wireless signals from an antenna and generating two video signals V1 and V2, two digitizing circuits for digitizing the video signals V1 and V2, a control circuit for merging the outputs of the two digitizing circuits, a digital-to-analog converter for converting the merged digitized signals back to a combined video signal, and a display control circuit for displaying the combined video signal. Asynchronous condition may happen when displaying different fields of the two video signals V1 and V2 in the same time. And the control circuit uses a storage method which controls the storage of a specific field of the video signal V2 or a data retrieval method which controls the retrieval of a specific field of the video signal V2 to solve the asynchronous problem.