With my genetics hat on I'm afraid it's not even that simple! Transcription errors occur even through cloning or general growth, it's one of the reasons variegated growth can revert to plain growth and cancerous growths occur.
True eds! That is exactly why we have to define 'clone'. A clone has the same DNA as the original plant. Any deviation or departure ------ is then not a 'clone', or no longer genetically the same as the original. Uncertainty about the DNA sequence (when compared with the original) is something we have to just deal with. But when getting down to the actual definitions ------ as in identical DNA, then it's true to say that a clone isn't a clone if it doesn't have identical DNA, and so for correctness ----- can't and should not use the same clonal name for a non-clone, even for a plant that just so-happens to have the DNA changed due to mutation. That's not a problem. It is just definition.
Somebody still has a choice to use the same clonal name for what they like - but that would then be based on 'assuming' same DNA (or some other reason). But if something is clearly different - such as mutated, then it makes sense to not use the same clonal name - due to obvious visible feature differences ----- such as nearly all or every leaf of an orchid being variegated - while all the other members have no variegation.
Here, I'm just limiting the field to orchids. Definitely not even going to go there with non-orchids, such as some variegated monstera.