I was looking at flights to Europe for May, and I noticed something strange. On some routes, such as on CLE-ORD or CLE-IAH, sometimes there are two flights scheduled leaving at the same time, one CO operated 737 and one UA operated A319. What is interesting is that the seat maps are not available for the UA operated ones neither on continental.com nor on united.com Does this mean the plan is to have UA A319s fly these routes and replace the 737? If yes, why the duplication? Here is an example:

Flight: CO1436
Aircraft: Boeing 737-800
Depart: 4:00 p.m. Wed., May. 2, 2012
Cleveland, OH (CLE)
Arrive: 4:23 p.m. Wed., May. 2, 2012
Chicago, IL (ORD - O'Hare)


Flight: CO371
Operated by United Airlines.
Aircraft: Airbus A319
Depart: 4:00 p.m. Wed., May. 2, 2012
Cleveland, OH (CLE)
Arrive: 4:27 p.m. Wed., May. 2, 2012
Chicago, IL (ORD - O'Hare)