After defeating Skolas, I was excited to receive two Elder Ciphers amongst other rewards. The glitch begins when you travel to see Variks, The Loyal to start the reward process for your Elder Cipher. When I chose my first Exotic reward (Dreg's Promise), I could only choose the weapon I wanted once, and it counted for both Elder Ciphers, rather than being able to choose a separate gun for each Elder Cipher. Now I currently have 2 Elder Ciphers with the same Exotic, because I was unable to choose a separate reward for each. tl;dr: I'm not able to choose two Exotic gun rewards for two Elder Ciphers, I can only choose one Exotic weapon that counts for both Elder Ciphers.