title: Preventing double HTTP POST
body: <p>I have made a little app for signing up for an event. User input their data and click "sign me in". </p>
  
  <p>Now sometimes people are double in the database, the exact same data that got inserted 2 times very quickly after each other. This can only mean someone clicked the button twice, which caused two posts to happen. </p>
  
  <p>This is common web problem, as credit card apps and forum apps often say: "Clicking once is enough!".</p>
  
  <p>I guess you could solve it by checking for the exact same data to see if the post is unique, but I wonder if there are other methods.</p>
  
  <p>This ofcourse does not count for ASP.NET webforms, because POST doesn't matter as much.</p>