Mocked values mismatch with MagicMock

Question

I am working on a python project, where we read parquet files from azure datalake and perform the required operations. We have defined a common parquet file reader function which we use to read such files. I am using MagicMock to mock objects and write test cases, when I ran the test cases some tests were failing because they have mocked values of some other test cases. I didn't understand this behavior completely. Below is my code

utils/common.py

def parquet_reader(parquet_path: str) -> Tuple[Dict, int]:
    table = pq.read_table(parquet_directory_path)
    return table.to_pydict(), table.num_rows

-------Test01-------------

PARQUET_DATA = {
    "se_vl": ["530"],
    "l_depart": ["028"],
    "r_code": ["f5"],
    "r_dir": ["W"],
}

NUM_RECORDS = 1

TEST_CAF_DATA = (PARQUET_DATA, NUM_RECORDS)

def test_read_from_source():
    common.parquet_reader = MagicMock(return_value=TEST_CAF_DATA)
    obj = next(read_from_source('path to file'))

    assert obj.se_vl == "530"

-------Test02-------------

from utils import common

SAMPLE_DATA_PATH = "src/schedule/sample_data"

def test_parquet_reader():
    rows, _ = common.parquet_reader(SAMPLE_DATA_PATH)

    assert rows["key_id"][0] == 345689865
    assert rows["com"][0] == "UP"

When I run all the tests(total of 240 test) than the variable 'rows' in test02 holds the data for test01 (PARQUET_DATA). However I fixed the above issue using patch. But still confused as why such behaviour using MagicMock?