The exotic duplicate is a separate issue and I put my comments on that in a different post. I don't understand what you mean the exotics are dropping lower than your light? Exotics drop at +5 of you base power (power without any mods). So if you have gear with all legendary mods then the exotics will drop at your same power level. I don't understand why bungie would create such a confusing and non intuitive power system when they didn't have to. After a player hits 280 everyone will have legendary mods so the +5 power bonus is no longer special it's just the norm. So either the mod should count towards your base power as far as drops are concerned or don't have the power bonus attached to the mod. If mods were hard to come by or their were exotic mods I might see the point of having the +5 power on them if exotic mods were +10 but again after a period of time and I mean short period of time everyone will have those mods and it just becomes the norm.