Sandeep is right. Just put a break point into both handlers, run your app in debug mode, hit a key and see where you stop first.
Normally, your handlers should be called in the same order of the assignements:
...
{
MyEvent += MyEventHandler1;
MyEvent += MyEventHandler2;
}
void MyEventHandler1(object sender, EventArgs e)
{
}
void MyEventHandler2(object sender, EventArgs e)
{
}