Should be no problem pairing to both. If it was not possible, the bluetooth pairing program would tell you so. I have 2 headsets paired now, one in the ear and one pair of ear-Muff style.
So connecting to your BB and a headset or keyboard simultaneously is possible?
I'm thinking of being bridged to the BB answering calls on a headset and responding to emails on the PB (potentially with a BT keyboard) at the same time.