Sideshow has been doing this a lot lately - Vader, Bossk, IG-88, Fett to name a few. The difference are mostly cosmetic (better paint apps for "better film accuracy" but some revised accessories (new ammo belt for IG-88, different hands for Vader, new head for bossk) but they are also removing the deluxe display bases from these releases as well.
4-LOM (RAH) was made by Medicom before but sold through Sideshow, so this is there first official version of the character.
What also sucks is the Sideshow releases in the past 3-4 or so their have had C-3PO, R2, Fett, sandtrooper, snowtrooper, and now they'll be distributing the superior Hot Toys versions. Obviously this double dipping was inevitable once HT announced they'd be doing 1:6 SW figures but you'd think the duplication of characters in that scale would have been spaced out better.