I've never used the same scented shaving cream with aftershave... Although I don't really use aftershave. I use a post-shaving balm/gel/cream and then, before getting dressed, put on cologne.
I use whatever shaving cream scent strikes me that morning. I even use different post-shave treatments on different parts of my face & neck! I usually use Trumper's Skin Food on the face & cheeks, and then (after the skin food dries) I slather on some NancyBoy post-shave gel on the neck. The scents are distinctly different, but I never notice any clashing at all... And by the time I put on the cologne, a good few minutes has passed so that the only LASTING scent is the cologne.