building conflicting packages from a single spec

[Pádraig Brady]

Is $subject possible?

For example generating subpackages like:
  %{name}-small-but-slow-binaries
  %{name}-fast-but-big-binaries

I can %prep and %install into separate areas,
though was then wondering how to adjust
the buildroot for subpackages?

Are any other techniques possible?
I suppose I could manually set conflicts,
and then move binaries post install,
though what happens if mv is one of the
binaries for example?

cheers,
Pádraig.