The CVC3 was an RGB dimmer that operated using the PLink protocol that preceded the CVC4.

We do not recommend mixing CVC3s and CVC4s on the same project.

Although the CVC3 and CVC4 use the same PLink protocol, making it possible to mix them, there are significant differences in the dimming curves between the two models. 

It is possible to program separate dimming curves in your lighting control software; however, for ultimate simplicity, we recommend that CVC4 are used in place of the CVC3.