the paterson system 4 uses plastic reels.
Jobo reels have a special plastic tab, which can be pushed in after the first roll is loaded to prevent the second roll from over lapping. there are of course other, simple methods for loading 2 up 120 rolls on a single reels (paterson or Jobo) with no risk of overlap.
Perhaps we should do out next video on that.
There is no way to load 2 rolls of 120 on a single SS reel, unless of course you tape the two roll together....