I move the old queen out of the hive as well when I do an artificial swarm/split.. However I don't leave all the cells in the hive. I use them for other splits, or simply destroy all but two of the best "looking" ones.. Best looking... hard to explain, the biggest/nicest looking I guess is how it is best put.
I know some who claim only ONE should be left, but, what if the queen in that cell does not emerge for any of many reasons? There is a chance Both will not emerge, and there is a chance if both DO emerge one will swarm.. It is a matter of odds with me.. two cells left give me better odds ONE will emerge.. If BOTH emerge they may fight it out. If one emerges before the other, the first out is likely to kill the second one before she can emerge...
Calculated risk I guess best explains it.