Based on this product's specifications, here are some alternatives and similar models
Double Frame KOS aluminium for KOS66 series, model 664082
Summary description:
Double frame KOS in aluminium (model 664082) is an accessory designed to hold two modules or devices in the KOS66 mounting system. It provides a durable aluminium surround that organizes and secures paired components in wall installations. Suitable for residential or commercial electrical and low-voltage setups where a two-module frame is required.