duplicate bad entry in the bgc-s index

I am not sure where to report this and it is a minor issue.

For wmo = 4902627, cyc = 18, the bgc-s index https://data-argo.ifremer.fr/argo_synthetic-profile_index.txt.gz file has a duplicate extra file row with bad data:
```
file date latitude \
30 meds/4902627/profiles/SR4902627_018.nc 2024-03-04 17:25:00 42.484
31 meds/4902627/profiles/SR4902627_018D.nc 2024-02-23 23:52:00 NaN

longitude ocean profiler_type institution \
30 -60.269 A 836 ME
31 NaN NaN 836 ME

parameters parameter_data_mode \
30 PRES PSAL TEMP DOXY CHLA BBP700 PH_IN_SITU_TOTAL RRRRARR
31 PRES PSAL TEMP DOXY PH_IN_SITU_TOTAL RRRRR

date_update wmo cyc
30 2025-08-27 21:56:11 4902627 18
31 2025-08-27 21:56:00 4902627 18
```
When using argopy (and user mode is standard), this WMO is filtered out because it chooses the 2nd (bad) row and then CHLA_DATA_MODE becomes "".

I wasn't able to test the whole index for other duplicates. Perhaps there are others.

#### MCVE Code Sample

```python

import numpy as np
from argopy import DataFetcher as ArgoDataFetcher

wmo = 4902627
cyc = 18
region = [-70, -40, 20, 60, 0, 1000, "2024-03-01", "2024-04-01"]

# 1) Fetch in expert mode (so nothing gets dropped by standard-mode filtering)
fetcher = ArgoDataFetcher(
mode="expert",
ds="bgc",
src="erddap",
params=["CHLA", "PRES"],
).region(region)

# 3) Show what the Argo synthetic-profile index says for the same float/cycle
idx = fetcher.fetcher.indexfs
idx.query.wmo([wmo])
idf = idx.to_dataframe(completed=False)
idf[(idf["file"] == target_file) | ((idf["wmo"] == wmo) & (idf["cyc"] == cyc))]
```
shows output above