Recrystallization of salts with similar solubilites

If you had two solutions, for example, 100 ml each of 0.5 M $\ce{RbCl}$ and 0.5 M $\ce{NaBr}$, at 20 °C, where the salts have very similar solubility in water, and you mixed the solutions, and allowed the water to evaporate. Would you theoretically end up with equal number of moles of $\ce{RbCl}$, $\ce{RbBr}$, $\ce{NaCl}$, $\ce{NaBr}$? If not, is there an equation or methodology you can use to determine how much of each salt you'd end up with?


