Are my keys used or not?

Nope, unfortunately, it is not possible.

Yes you can, give me all your keys and ill see which one is good.

If you activated the games on your account, you can try the key, and if you get 'duplicate', it's not activated yet. If you get 'already activated', well, then, you know.
It's only my conjecture, but you won't activate keys twice, that's for sure.

Well
If you already activated one set, you could try activating the other?

If it's the Namco Bandai bundle, you can run them past me too. I just redeemed those.

Steam needs to implement a feature to input a key and it tells you if its been redeemed or not.

If you want to give them away, you can provide both keys from the bundles to the receiver and tell them to try which one works.

if you aren't sure if some keys work, give them to friends (which won't be offended if they don't work xD ),
use them in alt accounts to farm cards (if they game has cards, of course),
dump them here
or just make an unofficial giveaways here in the forums (like telling people to post and them picking a winner with random.org... and say they might not work).

just some ideas as there's no way to check if a key isn't used or not.

If you have 100% sure that the at least one of keys for the same game are not used, just do the giveaways and them give the winners both keys and tell them that only one of them will work.

I see this so many times with people mass buying bundles,they take the time to buy bundles but no time to organize the keys and mark them used or delete them from a list of keys.

Yeah it takes time,but in the long run you will avoid this..

Short answer is no way to find out if they work without giving them to someone to try and then they will own it.

Not all games allow you to see the keys if your lucky and you have some that do then you can check this way,I wish Steam did allow you to see all keys,but i also understand why they do not,as they use that as an extra step in case your account is taken,you can prove its yours by providing keys though this would imply you know the keys,in your case it might not help lol.

Anyhow all i am saying is maybe lesson learned to keep better track of bundle keys and less time buying a ton of them and praying you remember.

If you are sure you have the keys twice and only used once.
make a GA with one key. if it doesn't work give the winner the other key.. no problem.
you have seven days to give him the keys

if you are not sure if both keys were used. better get some more keys ;)

If you have activated the keys on your account then it's easy, you should try to activate the key on your account and I think you'll have 2 messages:

• You already own this game
• This key has already been used

You could also follow TinyPurple advice too!