It might be a bit more common than you think!
I have used it in a commercial setting in two ways,
roasting the base blending bean at two different levels and batch roasting
a preblend at two different levels.
There's no reason not to, especially with really good beans, such as the ones on beanbay.
The technique is used to build complexity, bring subtle nuances to a blend and to highlight
the different roast level characteristics of some useful beans.