I haven't done it on CO, but it used to be with HP that you could beat the system by playing musical chairs, but they "fixed" that a couple of years ago.
p.s.
On those "change of gage" flights, (you know, like the little 737 that leaves RDU and "grows up' to be a 777 at LGW) you get 2 BP's but only one credit for the common flight #.
[This message has been edited by snake (edited 10-24-2003).]