After Effects' Channel Info kind 2 "(copy)" was imported as R, G, B or A.
EffectCraft's EXtractoR resolves those names through the footage's aux planes
first, and an OpenEXR keeps its own R/G/B/A planes, so "(copy)" read the
original file plane and dropped what an earlier effect did to the channel.
"(copy)" is now a reserved EXtractoR channel name (EXTRACTOR_COPY) that the
CPU and GPU renderers never look up in the aux planes: it is the input's own
channel of the same position. The importer writes it for kind 2.
Render regression: a modified input buffer with same-named R/G/B/A aux planes
of other values; GPU parity case with (copy) on an aux scene with R/G/B.