Like in Esperanto, in many Slavic languages one can stack affixes on top of each other, even those of the same meaning. The latter often ends up sounding awkward or exaggerated, but that may be the intended. In the case of diminutives, two are not uncommon, meaning just an even closer level of affection, but even more can be observed:
- máma = mother
- mamka = mum
- maminka = mommy
- maminečka = dearest mommy
- mamušinečka / mamininečka ~ awkward but the meaning is clear
In Esperanto the meaning is carried by -nj- / -ĉj- which seems impossible to duplicate within one word, but I suppose an -et- would also be understood. Can one purposely repeat it or is using the same affix twice forbidden by the rules? I'm thinking of, for example, bebeteto for a really tiny baby or domegego for a really immense mansion.
Tekstaro does not seem to have any examples of such thing, but that may just mean it's something one wouldn't put usually put in print.
I know pra- can be repeated, but I don't know if that's an exception.