In my experience I have seen several questions like this closed as "too localized".
I was getting the same error than the OP, but for a rather cryptic reason (some TOAD internal error), I couldn't find any post about my specific issue, but I found that question. It wasn't helpful because the error clear states there is a duplicate column, and he has a duplicate column. For me this is too localized because it only helps him. Is very unlikely someone else is going to have the same list of columns.
I tried to flag the question as "too localized", but I couldn't find the option for it, so I thought the correct way was to flag it for moderation attention.
My flag got declined and I got this answer:
Please use standard close votes or close flags for this instead of flagging for moderator
That made me realize I probably missed the option for too localized, so I continued searching and I found this.
According to that post I should flag the question as "Off-Topic" and give a reason. But this question is not off-topic, is not either lacking information, because he provided enough information to solve it.
Is that question too localized or is it valid?