Silly collision question?

It seems like I have made something like this before, and I don't remember this problem. I am trying to make a doormat that will notice when an avatar stands on it, greet him, and open the door in front of him.

I used a collision_start event to figure out when he stepped on the mat. Seems simple enough. But when he walks on to the mat, it fires something like 5 times. Move slightly, fires again in multiples. Is there any simple way to deal with this?

I have thought of a couple of ways, but they seem too much for what should be simple. I could keep track of each avatar to collide for a certain time, and then check each collision against that list. Or I could set a timer and not recognize any new collisions for 1 sec.

Thoughts/ideas?

my stupid solution: I put welcome mat scripts to llSleep for a time slightly less than the amount of time the door waits before closing (assuming it closes automatically). Keeps them from babbling too much when a crowd walks in.
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Hi,

what you can do is look at a list if detected key or name is on the list.
if not say your message and add the name/key to the list.
and if the name already on the list do nothing.

with a timer you can reset the list every certain amout of time.

http://lslwiki.net/lslwiki/wakka.php?wakka=llMinEventDelay

That might help. It will cut down on the frequency