Answer

It is best to avoid covering the same listening area with different loudspeakers, but mixing and matching different loudspeakers for different jobs is fine. For example if you are using K.2 loudspeakers for your mains and CP for your monitors, then this will work perfectly fine. 

What is not recommended however is attempting to “array” CP loudspeakers alongside K, K.2, or KW Series within proximity. For broader coverage, two or more loudspeakers may be splayed (aimed so that the horizontal coverage of the loudspeakers has minimum overlap). For best results, this should always be done with identical loudspeakers.