Steps to reproduce:

1. Create host prototype, filling in the Group prototypes field with some macros.

Result:
See screenshot...
See log file...
See memory dump...
Expected:
A group is created for the first host, and a single host falls into this group. for the rest, the message appears: Cannot create group: group with the same name "xxx" already exists. It is not necessary to create a group, it is necessary to place hosts with such a prototype in this now existing group.