validate binding names don't conflict

.changeset/strange-dingos-listen.md

@@ -0,0 +1,19 @@
+---
+"wrangler": patch
+---
+
+fix: validate that bindings have unique names
+
+We don't want to have, for example, a KV namespace named "DATA"
+and a Durable Object also named "DATA". Then it would be ambiguous
+what exactly would live at `env.DATA` (or in the case of service workers,
+the `DATA` global) which could lead to unexpected behavior -- and errors.
+
+Similarly, we don't want to have multiple resources of the same type
+bound to the same name. If you've been working with some KV namespace
+called "DATA", and you add a second namespace but don't change the binding
+to something else (maybe you're copying-and-pasting and just changed out the `id`),
+you could be reading entirely the wrong stuff out of your KV store.
+
+So now we check for those sorts of situations and throw an error if
+we find that we've encountered one.