Variables-newbie

I start the same movieclip with two different buttons (1 & 2), and they have
variables:
1: a = “1”
2: a = “2”

in the last frame of a movieclip I have this script:

if (a= “1”) {
getURL(“http://student.umb.no/~dmunne/konserter/index.htm”);
}
if (a= “2”) {
getURL(“http://student.umb.no/~dmunne/nederland/index.htm”);
}

I thought that now, when I press the first button, it plays the movieclip and then goes to the first URL, and when I press the second button it plays the movieclip (the same as button 1) and goes to the second URL.

Why does it make the browser open both URL’s when I test the movie?