I'm submitting a...

[x] Feature request

Current behavior

If you use custom ids for i18n translations and you have multiple elements with that custom id that have different contents, you will only get one translation extracted.
e.g.: <div i18n="@id">Hello world</div> and <div i18n="@id">Bye world</div>
Only the first one will be extracted, and they will both be replaced by the same content when you use translations, but will be different in the source language.

Expected behavior

We should throw an error, or at least print a warning when we extract if we have the same id for different contents.

What is the motivation / use case for changing the behavior?

Avoid errors.