The question of Advanced Sensors+Decloak relies on timing details we simply don't have for X-wing. The two actions depend on each other, and depend on when conditions are checked. You can't cloak if you already have a cloak token, and you can't decloak unless you do. So figuring out what you can and can't do with simultaneous cloak effects relies on knowing when those conditions are checked, and what the detailed timing is for simultaneous abilities. We don't know that. Honestly, I'm not sure FFG actually knows that, because I haven't seen anything that hints at some secret detailed timing model.
So it'll be whatever FFG says it is.
The question of decloaking twice for a single dial is safer, IMHO. One dial, one opportunity to trigger an effect, one decloaking. Honestly, anyone who thinks they'll let you double decloak hasn't been paying much attention. The Phantom is already a crazy maneuverable ship, you really think they're going to let you pull a speed 5 move sideways before your normal action? Even though the rules on this one are solid, even if they weren't you had to know that wasn't going to work.