Comments block bug. PS 1.4.1.

[Amazzing]

Hello!
I faced an issue about comments block:
After adding a simple comment in front office, the following writing appears instead of “post comment” button “You should wait 30 second(s) before posting a new comment”.
Well, that is OK, but when I refresh page (f5), a clone comment is posted and again same writing appears “You should wait 30 second(s) before posting a new comment”.
And this writing won’t disappear even after 180 seconds. And f5 always leads to posting a new clone comment.
I mean, pressing f5 works like pressing the button “post comment” and it clones comments again and again.

I haven’t made any modifications to productcomments module, so it looks like a default bug.
Does anybody know how to fix it?

And I have a question to prestashop exprerts.
How do you like the default comments module?
Is it safe? I mean, can it lead to site vulnerability by accepting text/code input from outside?

[Amazzing]

Well, may be it is not a bug, but a normal site behavior.
However, does anybody know how to change this setting?
So that pressing F5 wouldn't lead to reposting a comment?