For status they are doing the math in the background, if you have 12,001 miles in CO and 13,000 on UA, they will make you the proper status on both (assuming you have linked your accounts). Your accounts will remain separate through 2011
From this page:
https://secure.unitedmileageplus.com/MP1101OP.jsp
Combine your elite activity to qualify for a higher elite status in both programs.
We'll add the 2010 elite status miles or segments (EQM or EQS) you earned in Mileage Plus to the Elite Qualification Miles or Points (EQM or EQP) you earned in OnePass. For example, if you had 20,000 OnePass EQM and 5,000 Mileage Plus EQM in 2010, we'll upgrade you to 2011 OnePass Silver Elite and Mileage Plus Premier®. Plus, we'll do the same with your 2011 elite activity. If your combined activity in 2011 qualifies you for a higher elite status, we'll upgrade you automatically in both programs.
and
What happens if I don't register to combine my elite activity?
If you choose not to register, you'll continue to enjoy the same elite status you qualified for in each program in 2010, and your activity will count toward each program separately for 2011 status. Whether you register or not, your combined 2011 activity will count toward your status when Mileage Plus and OnePass are combined in 2012.
However, if you don't register, you won't be able to match your current status right now, or boost your current status in both programs by combining your ongoing 2011 qualifying activity.