the second CCH is a duplicate that double the capacity of RACH, PCH and AGCH, but the FCCH and SCH are not duplicated. The corresponding bursts are set to “idle” instead.
Regarding the merging of 2 LACs, yes, that is possible. As long as all the cells in both LACs have mCCCH. The drawback is quite obviously that you’re loosing 1 TCH ts in all your cells 🙂
One Paging Request = One CCCH Block (whatever the number of MS contained in the Pag Req.).