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No, they are not cumulative.
Also, Norton in particular has had false positive problems with some of the packs and/or updates in the last few years, but there has never actually been any problem with any of them as far as anybody could tell (and I have scanned them all with several other AV programs, and no problems were reported). I suspect that most of the problems resulted from the AV program's attempt to use "reputational" heuristics (and choking when it saw a Russian-based file with a relatively small number of downloads).
For more skin-pack-related info, check out this thread: https://riseofflight...g-related-info/