## Problem
When `get_cache_key(**kwargs)` is called with kwargs that already
contains `preset_cache_key` (which can happen when cache key is
recomputed in certain code paths), the call to
`_set_preset_cache_key_in_kwargs()` fails with:
```
TypeError: _set_preset_cache_key_in_kwargs() got multiple values
for keyword argument 'preset_cache_key'
```
This is because `preset_cache_key` is passed both explicitly:
```python
self._set_preset_cache_key_in_kwargs(
preset_cache_key=hashed_cache_key, **kwargs
)
```
And implicitly via `**kwargs` unpacking when `kwargs["preset_cache_key"]`
exists.
## Solution
Filter out `preset_cache_key` from kwargs before passing to
`_set_preset_cache_key_in_kwargs()`:
```python
kwargs_for_preset = {k: v for k, v in kwargs.items() if k != "preset_cache_key"}
self._set_preset_cache_key_in_kwargs(
preset_cache_key=hashed_cache_key, **kwargs_for_preset
)
```
## Testing
Added unit tests covering:
- kwargs with existing preset_cache_key (the bug case)
- kwargs without preset_cache_key (regression test)
- Verification that preset_cache_key is correctly set in litellm_params
Ishaan Jaffer