Models get downloaded at both artifacts path and .cache location

### Bug
When given custom artifacts path for downloading models, models get downloaded at both artifacts path and .cache both.
...

### Steps to reproduce

```
from docling.utils import model_downloader
self.artifacts_path = "./assets/models"
model_downloader.download_models(
output_dir=Path(self.artifacts_path),
with_layout=True,
with_tableformer=True,
with_easyocr=False,
with_code_formula=False,
with_picture_classifier=False,
)
```
...

### Docling version
2.52.0
...

### Python version
3.10.14
...

Any idea why this is happening? I saw the code also but didn't found anything suspicious.