No they wont cancel each other out. This isnt deconstructive interference, worst that can happen is that one roid binds much more strongly than another, effectviely making the second roid somewhat of a waste. I think they'd actually be quite nice together if they werent both nor-based roids, giving rise to prolactin levels. I know tren alone or deca alone gives my nips a run for thier money...Im on B6 the whole way through. I couldnt handle both together.