If both Nand flashes are inserted into the Nand sockets, with proper connections to cy68023, and then if you plugin the cy68023, the "Nand Device" label of Nandfg utility will reflect as "more than one kind of nand chips detected".
Is it not so for you? Please detail the behaviour seen.
Also, as I went through the Samsung K9K8G08U0B datasheet, I could see that there is only one CE signal. Which are the two CE0 and CE1 that you were talking about?