It is one of the very few omissions of the TomTom developers.
They allowed old versions to be overwritten by the new one with (almost no) checks. This has been known for a long time, even with modifications from the 1.9xx series.
There were more problems with it than benefits, that's why we recommended new installation with complete removal of the previous version (wipe cache)

But, not only within one edition then different editions as well ... that's not what i expected.
There is mixing of different codes, resulting in quite a ... mutant. However, it does not mean that it is good and reliable. Not at all recommendable.