Vestiges of dual in Czech and the instrumental plural case

I was thinking the other day why most Czech have such a hard time with the instrumental plural declension after the number two. Let's take a phrase like before/in front of those two young professors. The standard Czech rendering is před těmi dvěma mladými profesory, with three different endings, but it usually comes out as před těma dvěma/dvouma mladýma profesorama, with identical endings. The funny thing, though, that there a few Czech nouns that end in ma in the standard language, such as rukama (with the hands/arms), ušima (with the ears), očima (with the eyes) and nohama (with the legs/feet)  As can be seen, all these things exist in pairs, a remnant of the dual. When such words are coupled with adjectives, these also have to end in ma in the standard language: s těma velkýma rukama (with those big hands). If there is an "exception" for such words, you could have the same for the numeral two, which is dual: před těma dvěma velkýma nohama (with those two big legs/feet), which is already standard, and před těma dvěma mladýma lidma (with those two young people), which is not standard, but I propose it be. :)

Finally, Slovenian, another Slavic language, has retained its full dual declension, which is really similar to colloquial Czech in the instrumental plural. In Slovenian před těma dvěma/dvouma mladlýma profesorama would be pred tema dvema mladima profesorjema. For comparison's sake, no West Slavic language is so similar to colloquial Czech in this regard like Slovenian, a South Slavic language. In Slovak: pred tými dvomi/dvoma mladými profesormi, in Polish: przed tymi dwu/dwoma młodymi profesorami.