Only flood control doesn't work.
I don't agree with you. The flood control work fine if you've enabled it. For that you need go to JComments' settings and set appropriate value to parameter named 'Interval between post'. After this you'll need go to Permissions tab and enable 'Flood protection' for all usergroups you want to protect from.
I can send again again only if there is no comment between, It collects all send comments to one comment
By default JComments merges comments from one author if they are posted within 30 second and there are no comments from other author between them. In upcoming version you'll be able disable this feature through JComments' settings. In current stable version (2.2.0.2) you could do it too but you'll need to change value in database.
1. Open phpMyAdmin
2. Select your site's database
3. Execute next query:
update `jos_jcomments_settings` set `value` = '0' where `name` = 'merge_time';