Are perfect-reduplication and quasi-reduplication related?

[ReneZ]

For example, in a sentence like "The dog dug a hole," dog and dug only differ by one letter, but there's no intent to duplicate and the similarity is coincidental.

This type of coincidental similarity can happen of course, but given that it is coincidental, it is likely to be quite rare. In the Voynich MS it is far from rare - it is one of the features that people have been wondering about for decades now.

It can be a feature of the original  text (if there is one), or it can be a feature of the encoding, or more generally text generation.

Reduplication is a known feature in quite a few languages, but quasi-reduplication probably less so.
However, also this exists in Thai, as I may have pointed out in the past.
While exact re-duplication is mostly used to soften a term, quasi-reduplication is used in spoken language in order to make it pleasant-sounding.

'Fun' is 'sanuk'. This is quite often expressed as 'sanuk-sanaan'.

Both can be used together. The word 'ba' (with a falling tone) means 'crazy' and is quite a strong word.
It is softened up by saying ba-ba-bo-bo.

This is written: บ้าๆบอๆ   by the way, and the ๆ is a reduplication symbol.