Companies have stated certain balls have hybrid coverstocks, a combination of pearl and solid, but never have stated percentages of each.  The first I have noted is Motiv in its new Jackal offering of a 2:1 ratio.  Marketing??  Or have all the other hybrids been 50%/50%??

I look at hybrids this way. Since surface dictates length, a shiny one will react like a pearl and a dull one will react like a solid.  So, in that respect it's marketing. 

Joe Bowler has had success with a solid, so his natural response is to buy the pearl version of that ball, and the companies know this, so they create another "need" for Joe Bowler by adding a hybrid.

Each hybrid ball can have varying mixtures of solid and pearl, for lack of a better explanation. 

For example, let's say red is the solid and blue is the pearl.  No two balls are exactly alike.  They will have varying mixtures.  Also, every resin ball starts out with a base (solid) and then an additive can make it a pearl, if I understand correctly...

It doesn't have to be a solid and a pearl. Hybrids can be any mix of different coverstocks.  Two different solids for example.

Lane #1 Hybrid Dirty Bomb for instance: two Brunswick PK solids mixed, no pearls. The Tsunami H20 may have been the same thing.

I'm not aware of any double pearls but that's not to say there aren't any. The UFO Alert sure looks like pure pearl on the shelf. I'd also like to know what the more recent double solids were.