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Hello Salento and zanipolo,
I heard back from Gareth earlier today:
"Hello Brian,
Thanks for getting in touch. CTS8489 and CTS8862 were both included in the SNP pack to maintain comparability with the older Geno 2.0 chip but until now they have been regarded as equivalent i.e. all T men tested either were positive for both or negative for both. You appear to be the first known example who has CTS8489+ and CTS8862-.
This is perfectly possible as the two SNPs are in different locations and almost certainly occurred several generations apart.
FTDNA's tree has a slightly different list of SNPs in this section and for some reason doesn't include CTS8489 (possibly this location is not covered by the Big Y test).
Further investigation is needed here to help bring the trees up to date."