The BCC is defined per cell, not per TRX, not per TS.
a Handover Access towards cell B can be decoded as a Channel Request in cell C only if :
a) “target” TCH frequency (B) is the same as the BCCH frequency of C
b) target cell BCC in (B) is the same as the BCC in (C).
Whether or not the target TCH is on TS0 doesn’t really matter, unless the cells B & C are synchronized. But Sync Cells usually belong to the same BTS, and I doubt intra-BTS cells are going to use same frequencies 🙂
Now, if adjacent frequencies… frankly, ok, it *could* happen (as in “anything* could happen). But not much. Not much at all…