Another giveaway with same keys

Yes. Just be sure which keys you give out and don't resend those.

I can join it if you're looking for someone ^^

To answer your question though: yes you can.

I want enter your group :v

Keep in mind you don't get any CV for private or group giveaways unless you reach 5 entries.
I also don't believe it'll show you unassigned keys, so you'll need to search wherever you got your keys from and find which two weren't used.

If it's private, try using SGTools with an entry-cap filter to get 2 more entries, if you want to reach 5. You can keep upping the cap if people don't actually join the gib, and just (temporarily) blacklist the users who misused the filter.

For groups, not much you can do if you're unwilling to delete and remake, but in the future you can include a group that's empty other than for yourself, and use it as an emergency reach-5 group. :)