We're all the same guardian. Even the grimorie suggests it since Petra mentions us as 'the guardian'. Though it's all really loopy since it's canon that a shit load of guardians flocked to the reef and yet only one hunted down the wolves for the Queen. Though you could say the bounties were done by other guardians [spoiler]if there was more things to do and more of an open-world it'd blur the lines a bit....[/spoiler] Hell even Cayde-6 talks to a guardian in the tower and says to them 'weren't you in that strike to kill the archon priest?'