Reporting in on this one... I would discourage adding a second Clown after having one established in a tank. It is not likely to be a positive situation.
I tried adding a second Clown with NO success. Fortunately, I put the new clown in a plastic bubble (full of holes for water to pass through) and placed the fish-in-bubble a distance from the other Clown.
After some time my original Clown spotted the new guy and all heck broke loose between the two (through the plastic). Allowing a fair amount of time to pass, it was obvious that releasing the second fish would have been a bad decision. I do not believe there would have been a different reaction if the situation has not been controlled. I took the new Clown back to the LFS
(A side note: My decision to return the Clown to the LFS
was made after the store was closed... for two days. I put the little guy into a less turbulent area of my sump until I was able to retrieve and return him.)