Well, I suppose that it's fine to answer the two questions using the same chart if no major changes happened to any of the placements. There is a porblem though. It is related to your answer to this question; how come you were thinking of two different things at the same time?
See, in order to produce a question that is fit to be correctly judged by horary, you need to be In scared time and space when you think of the question. That is, the question must have been on your mind, you have a ll the needed information and the question was finally ripe to be asked. If one justs asks questions simply because they could use horary on them, there's a chance that the questions are not genuinine or not ripe yet because the person was not in scared space.
So, this is up to you to figure out. Were you in scared time and space? Were both questions genuine or were you simply think of question for horary use/training?
So? how come you were thinking of two different things at the same time?
If you were simply being Gem/Sag (thinking about everything at the same time natuarally) and were genuine, then use one chart. I figure the two minutes won't make major changes as long as the ASC or Moon degree hasn't moved much further along. But if you were just thinking of question simply to try horary, then neither chart will work.