Bronze Iridium was just the old name for Gold Iridium. Sometimes it went by just Bronze Polarized (without the Iridium title even though non-iridium polarized lenses would come later on). Soon after, Bronze then became more known for the base tint vs the mirror coating.  
 
We noted this in the 
Name Change page a while back. I imagine this is a similar situation as the Jet Black/Polished Black name swaps that happened around the same time.