How long have they been in there for, I wouldn't worry about it...
I have 2 percs too. At night one sleeps in the bottom front right corner and one in the top back right corner. Clowns aren't the greatest swimmers and so unless they have something to host they'll pick an area to sleep in and get pushed around by the current and they usually wind up in corners. Clowns also pick out territories when there are more fish in the tank. Mine used to hang out up high but they actually built a sort of nest in the middle of the tank where they won't leave and thats where they chill now. Clowns also copy each other. One of my clowns right when I got LS in my tank dunked his head into the sand and his tail was bairly visible (think he liked it cuz it was soft) and an hr later i go into my room the other one started doing it. Same happened where they slept both in corners. All im getting about is their wierd and have unnatural behaviors, don't worry
Jimmy