I hope you meant, a cross between BbPp and BbPp, else for bbpp x bbpp, all the progeny will be bbpp.
We need to work out a Punnett square to determine the genotypes resulting from the cross between BbPp and BbPp. The dyhybrid cross results in 16 different genotypes, of which a few have the same phenotypes.
It can be seen that there are 4 different kinds of phenotypes present, in the ratio 9:3:3:1.
