Many people suggest not mixing pruning groups. I have some mixed pruning groups and have no problem pruning as in the fall I prune type threes close to the base. Type twos are pruned in the spring when new growth sprouts. The bases are far enough apart that it is easy to tell which stems come from which bases.

In our zone type twos often die back to the ground so some people prune them as type threes which makes pruning a mixed planting simple.

I have mixed them and I do usually just prune the 2s as 3s but the problem I've had is the 3s usually grow much larger and much more vigorously. I have had 2s ultimately crowded out and killed by the 3s.