Probably the second guy entered at the same time as you.
Not exactly. That could be it, but it is very unlikely.
For example, when dealing with distressing on radios, only the name of the person that made the encounter and people that naturally spawn into the encounter show up on the WM-Encounter screen.
So... if George found an encounter, and then distressed and his 5 teammates spawned into the encounter, another player that found the encounter will still only see the name "George" in the encounter screen. The 220 HP rifler probably was distressed.