Duplicate target categories in calibration fit diagram

Some categories of calibration target appear twice in the calibration fit target diagram. One example is taxable interest income.

This may indicate that the diagram is grouping by an insufficiently canonical field, or that nested target categories are being rendered at multiple levels as if they were distinct sibling categories.

Expected behavior:

• Each conceptual target category should appear once in the calibration fit target diagram.
• If a target category has multiple nested levels, the diagram should represent that hierarchy intentionally rather than duplicating the category label.

Initial investigation target:

• Check taxable interest income and similar deeply nested target categories.
• Determine whether duplicates come from source/category parsing, variable naming, breakdown grouping, or target registry metadata.

Start by reproducing the calibration fit target diagram with taxable interest income and other deeply nested target categories. Trace whether duplication is introduced during source/category parsing, variable naming, breakdown grouping, or target registry metadata. Done means each conceptual category appears once, with nested levels represented intentionally rather than as duplicate siblings.