You certainly can!
The ideea is that as workload permits sectors can be combined and split again without having to change the frequencies that aircraft are on. You may have noticed that for a particular SID you are almost always given the same frequency after departure. By bandboxing 2 adjacent sectors (working them from a single position rather than 2) you can work aircraft in the larger airspace at one time (saving staff and also simplifying any co-ordination that may have taken place when they are 'split'). To facilitate this the 2 frequencies are 'cross-coupled'. This means that the controller transmits on both freqs simultaniously and when an a/c calls on one, the transmission is retransmitted on the second frequency. Therefore the pilots are much less likely to step on one another and it appears as if all a/c are on the same frequency.
Then when traffic loading requires the sectors to be split once more, a second controller simply takes one of the frequencies from the other, the frequencies are un-cross-coupled, and all being well there is a seamless transition from the pilots perspective!
I hope I've explained it well enough. If it makes no sense let me know and I'll give up and let another bod try to explain....
Even better, arrange a visit to our ops room and you can see for yourself!
Cartman