Applied by accident

Junior had been working as my right-hand man for some time now. Eventually they advertised the job he was doing properly so they could offer him promotion. They have to do this to be fair, in case anyone else in the company fancied the job, but bearing in mind he was doing the job anyway it was unlikely anyone would.
Somebody did, and for the past two or three weeks while they’ve been sorting out interviews Junior has been trying to find out who the other guy was and if he stood any chance. As it happened the guy worked on the same floor, but had never had any involvement in the work we do, so we regarded him as a dark horse, and had to take his application seriously.
In passing on Friday night, as I was leaving, the boss told me that I was going to be doing the interviewing (which I don’t think is right because the job would be the same grade as me, but I’ve done it before). I didn’t think that much of it anyway, because I couldn’t tell if it was some kind of jokey comment on the way out of the office, or if he was serious about the interviewing.
I asked my Team Leader on Monday if the boss was serious about me interviewing. She told me yes, but couldn’t tell me any details about it until tomorrow.
Tuesday came, and she took me to one side and explained that we were interviewing Junior, but not the other guy because he had pulled out. I asked why he had pulled out, and was told that he had applied by accident. He had confessed last week that he entered the wrong code for the job he was applying for, and accidentally applied for the job on our section, only realising when he got invited for interview. I can only imagine he missed out on promotion for the job he did want.
So we thought that was it and we just give Junior the job, but no. The boss hadn’t wanted us to tell Junior he was the only applicant now, and to go through the whole interview thing anyway, so he didn’t think it was a walk in the park. So on Thursday we have a room booked for most of the morning for one fake interview, and we can’t come back to our office after Junior’s interview, because we have to look like we are interviewing the other bloke.
Junior will find out probably anyway because he’s bound to se the other guy and ask him if he’s ready for the interview, to try and psyche him out or something.
Also, we found out that the boss was using these interviews as an excuse to miss a meeting he didn’t fancy going to. His boss told him that the meeting was more important to attend, which is how we got lumbered with the fake interview.