"2 or more items returned, instead of 1" returned by /splits-next
https://datasets-server.huggingface.co/splits-next?dataset=GEM/turku_paraphrase_corpus

```
{"error":"2 or more items returned, instead of 1"}
```

It comes from the MultipleObjectsReturned error in mongoengine.
"2 or more items returned, instead of 1" returned by /splits-next: https://datasets-server.huggingface.co/splits-next?dataset=GEM/turku_paraphrase_corpus

```
{"error":"2 or more items returned, instead of 1"}
```

It comes from the MultipleObjectsReturned error in mongoengine.