Append ignores time series index when data is identical? about pystore HOT 1 OPEN

import pandas as pd
import pystore

# create new store
pystore.set_path(path='/tmp/store')
store = pystore.store(datastore='datastore', engine='pyarrow')
test_eod = store.collection(collection='TEST.EOD')

# generate sample data
df = pd.DataFrame(
      list(range(10)), index=pd.date_range(start='2020-1-1', periods=10), columns=['data']
)
df
            data
2020-01-01     0
2020-01-02     1
2020-01-03     2
2020-01-04     3
2020-01-05     4
2020-01-06     5
2020-01-07     6
2020-01-08     7
2020-01-09     8
2020-01-10     9
# generate 2 overlaping sets of data
dfa = df[:-3].copy()
dfb = df[-5:].copy()
# 
dfa
            data
2020-01-01     0
2020-01-02     1
2020-01-03     2
2020-01-04     3
2020-01-05     4
2020-01-06     5
2020-01-07     6

dfb
            data
2020-01-06     5
2020-01-07     6
2020-01-08     7
2020-01-09     8
2020-01-10     9

# write data
test_eod.write('STOCK',data=dfa)
# query data
test_eod.item('STOCK').to_pandas()
            data
2020-01-01     0
2020-01-02     1
2020-01-03     2
2020-01-04     3
2020-01-05     4
2020-01-06     5
2020-01-07     6
# append data
test_eod.append('STOCK',data=dfb)
# query again
test_eod.item('STOCK').to_pandas()
            data
2020-01-03     2
2020-01-04     3
2020-01-08     7
2020-01-01     0
2020-01-02     1
2020-01-05     4
2020-01-06     5
2020-01-07     6
2020-01-09     8
2020-01-10     9