Define policy for duplicate DV columns in reorder_dv_cols and implement it #10
Description
Problem
- Multiple DV/loss columns can map to the same dmg-loc-dir-ds. Current behavior silently creates duplicate column labels, making selection and aggregation ambiguous.
Proposed solution
- Decide on a rule: sum contributions; take max/min for TIME; keep-first and warn; or find some other way. Consider how these columns are used in downstream code. Implement chosen policy and document it.
Permalink to context in #8 : https://github.com/OpenPBEE/Functional-Recovery-Python/pull/8/changes#diff-09ddbe9b47cd801ac2851f14da73cf459f44c2cd8c6d3f2a557541ff2a6bc4b2R514