Might that make it more difficult to add sentences, parse corpus sentences by computer, and have audio sentences match their text?
I do agree with your basic premise, however, and I have a couple more ideas we could explore the pros and cons of:
* A moratorium on adding sentences of a certain length in well-established languages. Ex: No more sentences of less than three words in English.
* A heuristic anti-duplication algorithm that forbids not just whole duplicate sentences, but near-duplicates.
But what if you haven't already registered? Let's keep in mind that we aim to serve non-registered visitors, and that the (limited) interfaces should be as usable and understandable as possible. Wikipedia already has separate interfaces for different languages, probably for similar reasons.