1990/07/12 Neptune, NJ, Green Parrot - This date originally solicited [https://happinessinheresy.com/nine-inch-nails-concert/philadelphia-july-12-1990/ 1.5 months] before as Chestnut Cabaret. Likely replaced by Drexel Univ. concert. Drexel and Chestnut Cabaret are located within 4 blocks of each other, so it's unlikely both happened. This guy's [http://musictravel.free.fr/concerts/concerts90.htm concert list] shows that he went to many early NIN shows around Philly and to many shows at the Chestnut Cabaret. If NIN had played Chestnut, he would have been there. Instead, he only went to Drexel. So I think that confirms that Chestnut was probably cancelled, maybe replaced by Drexel, and Green Parrot slotted into the original Chestnut date.
1990/07/25 St. Louis, MO 1227 - unlikely they played the same venue within a month of each other. The 6/21 date is confirmed with newspaper solicits, and this one has none. Only possibility is if the 6/21 date got postponed for some reason (first night of the tour) and made up on 7/25?
1991/01/22 Washington, DC 9:30 Club (1 AM show) - What was the proof for 2 shows on the same night? I forget.