In my tank I have my hammer and elegance close enough so that they touch when they both open up big. I left it for awhile to see what would happen and the hammer ended up pulling the tenticles that were getting stung in, the rest of the coral looked fine.
The tentacles that were touching eachother were not sweepers, just normal feeders.
I have since moved the hammer up a bit and it went back to normal the same day.
My conclusion is that it depends on how happy your corals are with their position and if they like their neighbors.