If you map the pixels on PB1 to be “left half” of the pixels, versus the ones connected to PB2 (“right half”) and run the same code (that uses mapping).
See Configuring multiple PixelBlazes for different segments of long strip
So long as the two PBs are in sync, they should calculate the same results and map correctly to the overall map. (So for example a music reaction program that puts moving colors out based on frequency bins and volume)