Thx for the tip :3 And good luck!

That's the question, I guess someone who only has the Free DLC's can use the main key. But I can't guarantee it.

Only Hawke's Bay is obtainable for free. You can't get Himmelstein without obtaining the other bundles, such as getting the Gold edition (this GA). I don't think having Hawke's Bay would affect any of this.

But I'm pretty sure one can have the bundle even if they have some of the other DLCs. I don't know why the last winner couldn't obtain it. I was able to when I had a code that gets me all the DLC even if I had a few others previously.

Are users who own either of those DLCs allowed to enter this giveaway?

As it relates to the permissions for rerolling based on owned content, GA creators are not allowed to block entry based on permanently free content, or for content that cannot be obtained by alternative means (as that latter point makes it no longer considered a collection of separate content, but unique content in its own right; In a sense, what you're actually giving away at that point is the exclusive content, with the rest of the package acting as extra components).
[Conversely, if you can obtain the means elsewhere, it still counts as a package even if it isn't such on Steam; As an example of that, Van Helsing: Final Cut was counted as a package by staff despite being a separate game, since you could obtain it for free by owning all three original games and syncing with the developer's website.
As a counter-example, Deponia: The Complete Journey contains exclusive director's commentary/etc, and was stated by staff to be considered a unique offering (ie, not a package) by that fact alone (though it having a unique APPID would also potentially be enough to see it treated it as such). This was the point where we received clarification from staff that the exclusive content didn't need to be gameplay related or meaningful, to have the package considered as being unique content.].
Just noting in case your intentions for asking were based in something other than soliciting the GA creator's preference.

[Disclaimer: As always, it's best to confirm rules directly with staff before acting on rule-related information, as staff members do change frequently (and at times have a limited or arbitrary grasp of site rules) and may not abide by previous staff assertions. Being able to directly reference a support ticket can avoid a lot of stress, especially where staff opinions differ.]

Gut okay, nächstes mal weiß ich es besser. Ich mache das nur aus Spaß und nicht professionell. Ich kann halt einfach nicht garantieren das der Key mit gemischten DLC's (egal ob free oder nicht) funktioniert. Da nicht jeder Teilnehmer die regeln gelesen und verstanden hat wollte ich nur netterweise darauf hinweisen. Dann gibt es auch später keine Missverständnisse.