I thought you only had one chance at a exotic drop either normal or hard? I was told if you did normal and then hard the only thing that could drop on the hard is helm/crux/sparrow or is that bs?

Bs. As mentioned above I do VOG normal Chest and atheon every week on all 3 characters, then do VOG hard chest and atheon on all 3 characters. I have gotten red death on normal followed by a MIDA I believe on hard. Then for Crota you can do normal and hard Crota. death singer however only gives rewards once so can do that on either normal or hard. So for one character if you do this you have 4 exotic chances from VOG, 3 from CE, then a chance from nightfall. So 8 chances per character. However, if your priority is the Vex I would just do atheon hard as you would have a double chance for that particular weapon. Same with the crux, would just focus on hard Crota. I have vex so don't worry about that, I don't have Crux but am not too worried about getting it as I would rather get truth, Thvnderlord, or universal remote so I still do normal and hard Crota. Once I get those I'd do hard Crota but since necrocasm isn't that impressive I'm not worried about it