I just checked mine.
Both entries (1500 x 2 = 3000) miles were still there in the CO account.
So I just linked my UA and CO accounts, moved all the miles into the UA account. Done. Zero miles left in the CO account.
I suppose they could try and claw them back out of the UA account, but I'm guessing that would be more trouble then it would be worth for them. I'll keep an eye on it.
Thanks, Continental, I enjoyed our relationship, but it's time to move on.
Now, where are those 50,000 bonus miles for the new United Explorer card I just signed up for, hmmm?