Windows host.id not unique

We are running +300 agents on Windows servers which have been setup using templated/automated installs. We now see that a lot of hosts share the same host.id value in our logging in Elastic which seems to be a problem when implementing the security rules, especially those that rely on patterns of consecutive events with the same host.id value.

What is a good way of moving forward? Can I alter the host.id? Does this have impact on other things? Any advice welcome.

Since we only have ingests coming from agents, would it work to just copy the agent.id into the host.id field in the ingest?