Yes, only the same models can be connected in parallel. For example, PBZ20-20 and PBZ40-10 cannot be connected in parallel.
The parallel operation is available for up to two units (a master unit and a slave unit) by using the optional parallel operation kit PK01-PBZ (PK02-PBZ for EIA inch racks or PK03-PBZ for JIS millimeter racks).
If you want to perform parallel operations with more than two PBZ units in total, PBZ SR series or PBZ BP series are the choice (Note that the frequency characteristics cannot be ensured by performing the parallel operation with more than three units on your own).
For the details, read the user’s manual – chapter of External Control, Parallel Operation, and Synchronization – Parallel Operation.
