GRK

> One workaround is that you can use an object with a property rather than a plain function: > ``` > > > >``` >``` > export default class extends...

This issue occurs in [non-special case of updateDynamicChildren](https://github.com/salesforce/lwc/blob/e0029ee71d72171f66c83de0735b6516414f0228/packages/%40lwc/engine-core/src/framework/rendering.ts#L947) If 2 new vnodes have the same `key`, they both would map to the same [`idxInOld`](https://github.com/salesforce/lwc/blob/e0029ee71d72171f66c83de0735b6516414f0228/packages/%40lwc/engine-core/src/framework/rendering.ts#L951). for the first vnode patching, [`elmToMove`](https://github.com/salesforce/lwc/blob/e0029ee71d72171f66c83de0735b6516414f0228/packages/%40lwc/engine-core/src/framework/rendering.ts#L957)...

Also, An actual error was thrown previously also, during other patches (props, attrs, etc...). It's just that now `patchDynamicEventListeners` is the first patching function. Remove this line and observe https://github.com/salesforce/lwc/blob/e0029ee71d72171f66c83de0735b6516414f0228/packages/%40lwc/engine-core/src/framework/rendering.ts#L590

see https://stackblitz.com/edit/salesforce-lwc-cjgdfveb?file=src%2Fmodules%2Fx%2Fapp%2Fapp.js for an example.

> The framework is misleading. The "Duplicated "key" attribute value" error is never thrown, it's just logged. In the example you've provided, there aren't any thrown errors that disrupt the...

Also, Now that I think of it, we should delay [call to getAttachedEventListeners](https://github.com/salesforce/lwc/blob/e0029ee71d72171f66c83de0735b6516414f0228/packages/%40lwc/engine-core/src/framework/modules/dynamic-events.ts#L36), until it is actually needed, unconditionally of API version. This is what allows props, attrs, event patch...

eslint-plugin-import(no-named-as-default): Should we transform `import userEvent, {event}` to `import { userEvent, event }` or should we leave them as non-fixable?