Well if you are entered to win good luck friend:)!

Appreciate that! Really want that second expansion- I actually ignored MKX on PC for a long time 'cause it looked like they weren't going to release the second expansion on PC. :X

(And then I won it near immediately after removing it from my site blacklist. :D Was pretty cool. ^.^)

I don't really know what else to do with the keys like that

Well, foremost, you have to decide what approach you want to take with the giveaway- do you want to ask for staff [through a Change Giveaway Game ticket] to change the giveaway to just one for the DLC? That'd let you freely repost any remaining keys in new giveaways without concerns over CV. It's easily the most respectable option, in those circumstances where the remaining keys can easily be reposted as new giveaways.

Do you want to give the keys to the giveaway winner? That'd allow them to commit CV exploitation, so it's typically not preferred, but SG has a standing rule that you're allowed to give extras to giveaway winners past whatever is required by the giveaway, so it falls comfortably within that, rule-wise. [It's also presumably why games that give "for-friend" gift copies upon activation can then have those gift copies freely reposted by the winner- functionally the single copy is all that's required to be given on SG, even if that's technically offering it at an inflated price. The gift copy counts as just a bonus which you're giving them.
On the other end of things, you can hold on to the keys and repost them, as you did meet obligations to the winner, but that's pretty blatant CV manipulation, so it's typically viewed the least favorably of all.

As far as dispersing the keys, if you don't feel comfortable with any of the above approaches, there are several ways to approach it. You can poke at people who commented on your giveaway (but didn't win) which you favored the comments of or just randomly selected, and see if they'd care for the keys. You can post an event thread and use a random number generator to select a winner manually, as an 'unofficial' giveaway. For the more self-serving approach, you can still benefit yourself and also avoid obvious CV entanglements, by trading or reselling the keys elsewhere (even so as to obtain other keys for giveaway), or even using them for giveaways on another site.

Basically, there's no real way to ensure someone doesn't benefit unduly from such an interaction, so in the end, the resolution is really based most just in you going with whatever approach you feel most comfortable with.

Where a Change of Giveaway isn't possible, publicly giving the key out in an event makes for the most visible act of respectability (and you can further that impression by associating it with expectations of the participants being low-win-rate/new users, people who have the game wishlisted, etc) , though, by contrast, throwing the key toward bots ends up earning you nothing more than a dismissive glance and possibly even scorn for your waste of a game. Certainly, even just receiving any comment of thanks ends up being all too rare with that approach.

Finally, for an especially interesting take on it, you can invite four entrants from (this giveaway) and invite them to a private/whitelist/group giveaway for the game. This'd avoid you getting CV, while also offering additional furtherance of the usual SG approach to giveaways. In fact, you could invite everyone from this giveaway [or at least, all that commented], and then just ask staff to delete the giveaway once you get a winner.

So yeah- in the end, there's no real firm approach to take, at any stage of the matter, past whatever you're personally comfortable with. Just.. the 'give it to bots' angle specifically, is probably the one you should avoid the most. I think even more CV-favorable approaches would be better considered (at the very least, they would be by me) than that approach.
[In fact, I'm deliberately choosing to enter just for the second DLC, so to my mind, I'm entering with the understanding that the 'CV cost' is worth just that DLC. As such, I can't say I have any consideration to what you do with the remaining keys- to me, those feel like they're still justly your property to dispose with as you please (given that you'd have fulfilled all obligations to me perfectly).]