Question

This is true with any other functionality present on the page. I don’t want the last event that happened before post back to happen again.

Answer 1

I believe you should take a look at the PRG Pattern (Post/Redirect/Get)

Post/Redirect/Get (PRG) is a common design pattern for web developers
to help avoid certain duplicate form submissions and allow user agents
to behave more intuitively with bookmarks and the refresh button

In ASP.NET:

1. POST – Submit button click causes HTTP POST
2. REDIRECT + GET – HttpResponse.Redirect()

MSDN, Redirecting Users to Another Page

In server code, you can programmatically redirect by calling the
Redirect method. The method sends a command to the user’s browser that
causes the browser to issue an HTTP GET command for the target page.

Few important notes regarding PRG pattern:

!!! The PRG pattern cannot address every scenario of duplicate form
submission. Some known duplicate form submissions that PRG cannot
solve are:

• if a web user goes back to the web form and resubmits it.
• if a web user clicks a submission button multiple times before the server response loads (may be prevented by using JavaScript to disable
  the button after the first click).
• if a web user refreshes before the initial submission has completed because of server lag, resulting in a duplicate HTTP POST request in
  certain user agents.
• if a malicious web user submits the form twice despite client-side safeguards and typical browser behavior.