SODE supports double jetways, and GSX can control them, if they are available in the scenery.
However, none of our airports use SODE double jetways yet. Maybe there's a couple at KLAS, but I'm not fully sure and I cannot check right now (away on vacation).
Note that, even if a scenery uses SODE double jetways, GSX will first check (asking SODE) for each jetway, if it can solve every door so, if a jetway won't solve at any door, it won't appear in the GSX menu so, in some cases, if you are not parked in a position that, on that specific plane, would allow both jetways to reach their doors, they might not appear in GSX even if the scenery *has* double SODE jetways at that gate, and this is entirely normal, since it wouldn't be correct to present to with a choice that we already know (from SODE) it won't solve.