Allow same locale under different domains

[andresgutgon]

Describe the feature you'd like to request

Hi, first of all thanks a lot for this project. Is awesome. I just started using and looks super nice. I'll try to explain my use case:
We need to build a page that is multi domain. NextJS support that but doesn't support having the same locale under 2 domains. For example:

example.fr
  |- fr (main locale no folder route)
  |-/en
example.be
  |-/fr
  |-/en

We have 2 use cases.

1. First one is supporting countries where the same locale applies. Like for example Belgium and France where french is one of their national languages.

2. The other use case is supporting the same language /en under different domains. The assumption here is that this is going to be duplicated content. But imagine you have a product that have different features based on the country you're. In that case you are explaining different things in the same language.

Not sure duplicated content affects SEO

According to this article Google: Duplicate Content is Not a Negative Ranking Factor at the end of the article you can see John Mueller (Webmaster Trends Analyst at Google) talking about it. Please let me know if I'm understanding wrongly what he says.

But in any case I think the use cases I exposed are valid concerns :)

Describe the solution you'd like

According to the code here NextJs is raising an error if you try to configure i18n with multi domain and same locales. Not sure if others parts of NextJS need to be changed to allow this. As I said I'm not a NextJS expert :)

Describe alternatives you've considered

The alternative is to allow more than one domain with the same locale 😄