Sure. It's possible to reconcile both statements -- but not without creating other problems. According to Clint, Casey stayed at Tony's on the night of the 15th. At around noon of the next day, George claims to have seen Casey and Caylee about to leave the family home. These two accounts are not necessarily inconsistent.
But then where was Caylee on the night of the 15th? She wasn't at Tony's, according to Clint. Cindy said she heard Casey and Caylee through the bedroom door on the night of the 15th. If Caylee was home with only the grandparents on the night of the 15th while Casey was spending the night at Tony's, (which is what you'd have to believe in order to harmonize Clint and George's statements above) Cindy would've absolutely known that she was caring for Caylee on that night, and would not have had to guess, or surmise, that the noises she heard through the door were presumably noises being made by Casey and Caylee. Logic dictates that Cindy would've asserted in no uncertain terms that she was watching Caylee on the night of the 15th. Cindy might have lied in order to suggest that Casey and Caylee were together, and safe, on the night of the 15th.
As I write this, I am leaning more and more to the idea that whatever happened to Caylee, happened on the night of the 15th on through the morning of the 16th. And the grandparents are intentionally covering things up a bit