Is it possible that duplication is mostly uncommon (aside from a few set phrases) simply because most languages don't have this feature? I'm not aware of any besides Russian. (Indonesian/Malay uses duplication, but it's to indicate plural, which is not quite the same.)

I don't have a problem with belbela versus belega, or altalta instead of altega. Although I would use -eg- more frequently, just out of habit, the other way strikes me as equally intuitively understandable. Of course, -eg- becomes more practical with non-monosyllabic words (paradoksparadoksa is a mouthful!).

I agree that belega sounds more natural, but perhaps one form doesn't have to displace the other: for example, belega could be a more formal way, whilst belbela could be a more colloquial way of expressing the same thing.

That's typically the approach used in Russian, come to think of it. "Красивый-красивый" is more informal than "красивейший", and you would not normally see the former in strict academic settings.

Tempodivalse:Is it possible that duplication is mostly uncommon (aside from a few set phrases) simply because most languages don't have this feature? I'm not aware of any besides Russian.

Afrikaans does. But you're right, probably very few languages.

Bruso:

Tempodivalse:Is it possible that duplication is mostly uncommon (aside from a few set phrases) simply because most languages don't have this feature? I'm not aware of any besides Russian.

Afrikaans does. But you're right, probably very few languages.

The World Atlas of Language Structures indicates that at least 278 languages use productive full and partial reduplication and at least 55 use only full reduplication. Among these languages are some Arabic dialects, Mandarin, Japanese, Hindi, Hebrew, Swahili, Thai, Tamil and Vietnamese.
The inclusion criteria must be pretty restrictive too, as Russian isn't in the list (maybe because its reduplications aren't considered productive or maybe because only the formal language is considered).

Bruso:

Tempodivalse:Is it possible that duplication is mostly uncommon (aside from a few set phrases) simply because most languages don't have this feature? I'm not aware of any besides Russian.

Afrikaans does. But you're right, probably very few languages.

Ancient Greek does too, but that's to show a specific grammatical tense. (In fact, if I remember rightly, it was a fundamental feature of Proto-Indo-European, the ancestor language of most of the European and Indic languages, but which most descendant languages subsequently lost. So it can be seen to a very small extent in Latin too, but not systematically; Sanskrit preserves it better.) The English Wikipedia page on reduplication shows that the African Bantu languages use reduplication pretty nicely too, to denote repeated action, which seems kind of logical. Chinese as well.

And yep, paradoksparadoksa is a bit big to get the tongue around (though only 7 syllables in all fairness, so hardly the longest word in the world). But if it's mainly a colloquial feature, those kind of words would tend to be short anyway. Paradoxical isn't a word that gets bandied around too much in informal speech (especially talking about degrees of paradoxicality). Maybe in your speech though, if you have a lot to say about Kierkegaard!