Unfortunately, I could not open your images to see what you are using as input. A lot of overlap means that the histograms are not descriptive enough for the objects you are trying to use. This can mean that the parameters are not good, or that simply the objects look the same given the level of noise you have (look the same for VFH).
I would suggest playing around with other feature descriptors (you have quite a few options in PCL). You can also find some more suggestions on the developer's blog (see Aitor's work), and past mailing list discussions.