Backends creation should not fail when using the exact same backend builder twice.

[rsupandi]

The customer is seeing that the backend creation does not fail and deploys as normal when the same name backend is used in production. However, in Viceroy it does fail. Viceroy should match production behavior.

As per the customer: "So either Viceroy exhibits stricter behavior than intended or Fastly compute@edge is less strict than intended".