No. Single-admission doubleheaders are almost never scheduled in advance; they most commonly occur as a result of rainouts. I suppose that unsold seats for a game that suddenly becomes a doubleheader could then be sold for a premium, but it's not as if people who already have tickets are suddenly going to be asked to pay more. By contrast, the problem with 7-inning doubleheaders was that customers had already paid for a 9 inning game, but if that game was rescheduled as a single-admission doubleheader, then were then being robbed of 22% of what they had already paid for. With the reversion to normal rules, a game rescheduled as a separate-admission doubleheader just preserves the status quo.