You know it's a shitty topic when Miles Fucking Vorkosigan doesn't want to use more words than he has to. Does he hope to avoid the inevitable conclusion of this by not telling his double? Like not actually going through with the whole explanation will make it not real somehow? (But it's not real for this version. Not yet. Ironically, all the more reason to press on.)

"I had one in combat. Cut off the legs of a courier we were escorting." And now, the very worst part. He's been over this so many times in his mind. Picking at the exact chain of events, every opportunity he had to change things. Skip over the details. Skip to the end. "Falsified my report to Simon, so he fired me." A medical discharge on paper - which is the explanation nearly anyone else would get. But Miles has had enough of lying to himself.