Hello, everybody.
This is not really theory, rather what we should think it really happened when Heller and the production ruin the whole plot with absurd explanations, dumb motives, pompastic twists. I believe that not only Heller had no clue about RJ identity when he gave the interview on season 5, but as well that the show starts to fall short of logic. The last thing is Partridge dying with the words Tyger Tyger in his mouth, instead of "Get X (here be RJ true name". This is so lame, unoriginal, and not the only stupid behaviour seen on the show starting from mid season 5 (for ex the Lorelei episodes and PJ, the titular Mentalist, incapable to make her reveal RJ identity...).

So, the only satisfactory eplanation NOW is that RJ is one of the Kirkland brothers. Otherwise you can't explain season 5 scene with the wounded RJ disciple in the hospital. If Kirkland is so determined to track down RJ to even resort to torture, he would have had no point in just finishing him off instead of getting the name out of him. The real RJ, his twin, would have acted like this. Besides the "fearful symmetry" clue, as someone has already noted, perfectly fits with the "twin" (triplets also allowed...) contrivance.

Every writer, screenwriter, storyteller (and viewer) knows that when the talk goes about twins, you should expect something cool happening...
Hope you didn't cock it, Heller.