You should be installing the same type of GPU in a single server. Mixing different types of GPU in the same server is not supported.
You can run different vGPU license types for each GPU within the same server. For example, the first GPU could run RTX vWS (formerly QvDWS). The second GPU could run vPC, and so on … depending on how many GPUs are installed.
However, this design is still not optimal, as high-end users and standard users require different types of CPU and other technologies due to their workloads, so bundling mixed workloads on the same server is definitely sub-optimal, however it is clearly possible. If budget allows, the workloads should be split out to run on more focused types of hardware.
Hope that makes sense.