Possibly, if you have list of densities and you have to match it. I can't think of any other scenarios in which it would be able to.
Hope I helped! :)
A. the same speed as the wave energy
If you are talking about ocean waves crashing into each other, they would probably mostly cancel out with just a bit of motion left over. If you are talking about things like frequency and amplitude, overlapping waves would combine and amplify or suppress each other, depending on their direction, position, frequency and amplitude. If the two waves complement each other, they amplify; if they conflict with each other, they are suppressed.