Duplicated tag_serial_number in animal metadata

[JolienGoossens]

When downloading animal metadata with get_animals(), you get a duplicated tag_serial_number for tags with two sensors and therefore two unique values for acoustic_tag_id. The output of get_animals should only contain unique values and thus for a tag with two sensors:

• tag_serial_number: one unique value
• acoustic_tag_id: the unique values of the different tag ids related to the different sensors

[JolienGoossens]

In animal metadata, tag_type and tag_subtype are also duplicated. If this is information on one tag (one unique tag_serial_number), then these values should also not be duplicated.