The ONLY way you can get different results is if you muck around with the spacing parameters, all the software is working pretty much the same under the hood. (Mike and I have discussed this at some length)
Strictly speaking, most of the software uses a random number engine, and so in some cases, if you massage the numbers enough, you can eeke out one or two more frequencies...but Chris is right, adjusting the spacing parameters is much more likely to generate more "valid" frequencies.