Wat? The system of gilding is quite simple: when you putting gild in item with slot, your stats cause the chance of appearing of additional slot after gilding. The gild will be succesfull in any way.
Not checked that moment for far long, wasnt double slot items buffed for just 30% of stats they have before, and 2 stats dependings for chance? Never heard about 2 gilds
Only item that has twos lots at the start is a Rangercape, the first gilding is free, the 2nd gilding is when you start to have a chance to open added slots like normal.