From SEO perspective - yes, it is bad. Actually the PageRank that you gain from the visitors finding this content through Google for example, will be separated between two pages. Sometimes they will hit test.aspx, sometimes test.html. If you have only page having this content, all "priority" will be given to it.
The search engines really care how much links you have to given resource. More links means lower page rank for the individual links (or Urls).
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