duplicate custom fields insertion

hi,
I’m using WordPress 3.0 and I insert custom fields into post.
>>>I select the type of custom field, I type the content, I press “add custom field”

On the screen, nothing seems to happen
but something in ajax [I think] add the meta into the bdd

When I click on “update” or “publish” the custom field appear on the screen… but is created a second time into the bdd

is it normal?
a solution to make it appear as soon as you click on “add custom fields” / block the “double update” which create a duplicate?

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