The last example in your comment is probably the most meaningful one:

```

<xarray.Dataset>

Dimensions: (x: 2, midx: 4)

Coordinates:

* midx (midx) object MultiIndex

* x (midx) int32 1 1 2 2

* y (midx) int32 3 4 3 4

Data variables:

a (x) int32 6 7

```

To avoid name conflicts, we could just discard the original dimension coordinates x and y. Like here above, "x" becomes a dimension without coordinate. In that example, when unstacking we would retrieve the "x" dimension coordinate like in the original dataset.

(note: I think it is now possible to have a dimension "x" and a coordinate "x" with different dimensions, but I haven't checked).