Huh? Could you elaborate on the no-mix part? I thought they were essentially the same thing (sidenafil and tadalafil), well, not exactly the same, but causing the exact same effect to the body, just with different release timeframes (~day vs ~few hours). It's not like bleach+vinegar thing? All the info I could find on dangers of mixing the two boils down to what is effectively an overdose, which you can achieve with either single one of them, by just chugging the whole pack at once.

which shouldn’t ever be taken together

If I had to guess, I'd say that the likelihood of there being any of the active ingredient of either in the capsules is as close to zero as makes no difference, and, if there is any, it's in doses so low that it would make even a homeopath blush, regardless of what it might say on the packaging.