To have both a 3-way co-axial and a 2-way component set both as part of the frontstage?
Yes, that's a no-no, even if they are the same brand. They'll have totally different performance levels, and the "worse" of the two will bring down the overall quality of the sound. Plus you'll have much more constructive/destructive interference, which will lead to frequency response problems that will likewise degrade the sound.