both modafinil and ampheatmines exhibit nootropic effects, and therefore do exhibit cross-tolerance. same as caffeine and amphetamine. essentially, all of these substances release dopamine and share pharmacology to a somewhat similar extent, therefore causing cross-tolerance.
i do however think that given the huge gap in potency between the two given drugs, any possibility of tolerance diminishing would be to a minor and perhaps unnoticeable extent.
in the end though, you know yourself best. so trial and error mixed with reading many anecdotes on the combinations or cycling of different stimulants would be the route to finding your definitive answer.