I really doubt that Jane is RJ just because I think writers/producers of this show are smarter than that.
Imagine how stupid would all the fans of this show (myself included) feel if they found out that the character they love and sympathize with is actually hartless and cold killer. I know I would be disappointed and feel kind of played because I cared for a character who is a monster.
That is why I doubt writers and producers would go that way.