dpb wrote:
....

Could be since there are duplicate bar codes it's the QA form mailed at
the same time that should have been mailed later. ....

Dangit, meant _different_ bar codes.

The Census web site FAQ indicates that's how they do tell duplicates
apart in the consistency response duplicate mailing sample so is at
least a possible explanation altho I'm sure those aren't supposed to be
mailed/received at same time but as a subsequent (on the hope you'll
have forgotten how you answered before if you were deliberately
misleading??? ).

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