`PadoDataset.ingest_obj` errors if same identifier

[ap--]

ds = PadoDataset(None, mode="w")
ds.ingest_obj(ds0)
ds.ingest_obj(ds1)

returns an error.

Temporary solution

ds.ingest_obj(ImageProvider(ds1.images, identifier="something_else")))
ds.ingest_obj(MetadataProvider(ds1.metadata, identifier="something_else")))
...

Todo:

• [ ] I need to define how two providers are merged, and what checks are going to be in place.