Checked it before toddling off to bed last night and have to say that there is no way on God's green earth that you can double those orings up. The collar will just barely get on the thread and get mebbe 2 turns before the rings compress and stop the process.
But! You may be interested to know, that you can use Free Center Fitting seals in Economy Fittings. I have a pack of Chaingun fittings and the internal base ring fits inside perfectly.