This is expected behavior: Xarray variable objects can wrap numpy arrays but generally they don't make copies of the underlying data. So it is possible that two different variables wrap the same numpy array, like in your example and in the example below.

```python data = np.array([1, 2, 3])

v1 = xr.Variable("x", data) v2 = xr.Variable("x", data)

print(v1)

<xarray.Variable (x: 3)>

array([1, 2, 3])

print(v2)

<xarray.Variable (x: 3)>

array([1, 2, 3])

data[0] = 10

print(v1)

<xarray.Variable (x: 3)>

array([10, 2, 3])

print(v2)

<xarray.Variable (x: 3)>

array([10, 2, 3])

```

Dataset.copy(deep=True) makes a deep copy, thus copying the underlying data.

Thanks for the quick response. I wasn't aware of this. I had assumed a new Dataset object will have data that is a copy of the underlying var_map data pass into it. Maybe this could be mentioned as a note in the docstring somewhere?