Thanks a lot for the helpful and prompt reply!Happy to help clarify, alanthia =)
OCBC$ are accumulated & pooled under the principal card holder's name. So yes, when you redeem points, you are redeeming from a pooled OCBC$.
However, do note that rewards will be capped at 120,000 OCBC$ per card anniversary year. So if you have both the Titanium Rewards Blue and Titanium Rewards Pink, the cap is at each card level. You can have 120k OCBC$ for the Titanium Rewards Blue and another 120k OCBC$ for the Titanium Rewards Pink.
^Sh