SPOILER DON'T READ FURTHER: How could Colqhoun have been Ives?

Maybe I wasn't paying close enough attention, but I see it said that Colqhoun was Col. Ives.

When he said "Not that long ago, I couldn't do that," and he said his wagon train got lost, and he "ate 5 men in three months, TB vanished," and Boyd interrupts him to say he already heard the story, suggesting that the event Colqhoun was talking about was the cave incident.

Someone suffering from TB the way he described wouldn't have made it in the military of that day, let alone up to Colonel. But even with communication lacking as it did back then, the command staff wouldn't have just said "Hey there guy who showed up in a military uniform claiming to be someone named Col. Ives. Take over this station!"

So clearly there WAS a Col. Ives, though perhaps they wouldn't know what he looked like?

I contend that Colqhoun killed Col. Ives, not that he WAS Col. Ives, as the Wiki and others are saying. Otherwise, what was going on with the story about going to a sanitarium? Was he on his way to a Sanitarium, ate someone, got better but still had TB, then joined the military, made the lifetime rank of Colonel and inexplicably found 5 more people to eat, this time curing his TB and leading to the events of the movie. Does not compute.

Please correct me if I'm mistaken.