Give all the buttons the same name but different values.

<input type="submit" name="action" value="button1">
<input type="submit" name="action" value="button2">
<input type="submit" name="action" value="button3">
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Then in your CGI the action parameter will be 'button1' or 'button2' or 'button3' depending on which is pressed.

my $query = CGI::new();
#assign value to $action
my $action = $query->param('action');
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you can then say

if ($action eq 'button1') {
#do your thing
}elsif ($action eq 'button2'){
#do another thing
}
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