Recording rules duplicates check

[r3code]

I've noticed that if I pass a folder to sloth validate it allows SLO duplicates to exist.

When creating a new SLO sometemes I copy spec from existing specs and forgot to change names.
Sloth perfectly validates and generates rules in such cases. But it can lead to duplicates of recording rules, and unpredictable behaviour durind recording.

We can deploy rules as prom, k8s, and openslo. Prom and K8S are almost the same and have equal slo_id format <service>-<slo.name>, but OpenSLO uses slightly different <service>-<slo.name>-<seq_no>.

So it looks like better not to mix spec types for the same service.
But if I have a folder with specs of one type, e.g. Prom specs for CLI generation, I want to know about slo duplicates in a folder or multifile yml.