It means that they took all the moving parts from the Miyota 8200 (i.e. the train wheels, balance wheel, pallet fork, mainspring) and installed them on a new support structure (the "bridges"). This new support structure looks very similar the support structure of the real RM movement. So effectively the Miyota 8200 has been "re-bridged" to look like the RM movement. But there are key difference between the RM movement's moving parts and the Miyota moving parts. As such it's not a "clone" movement, but rather a Miyota movement that was reimagined as an RM movement.