Extra HammerWatch copies gone?

I'm pretty sure you had to pay $8 to get the 2nd tier (4 HW copies), so why would they give 3 extra copies to people who didn't beat the 2nd tier BTA?
Or did their mail say that the buyers with the 4-pack would receive 3 more copies?

I didn't get them at all.

I am not entirely sure but I don't think that it was intended to give 3 extra copies to already gifted giftable URLs of the game. Instead, the intention was to give the original person who purchased the bundle extra copies.

Instead of each bundle getting 3 extra copies, each giftable URL got extra copies, meaning a full bundle got about 16 copies (?) if I am not mistaken. This doesn't look intended to me.

I assume they removed the extras from those already gift URLs. That's just my assumption though, I might be wrong.

Edit : Quoting your post "anyone who had purchased the HammerWatch Daily bundle".

Yup, same thing happened to me. Got the same email, had 3 gift links added on my bundle page and now they're gone.

I think they added them to people who bought the daily bundle but didn't go for the 4-pack. Would make sense since the BTA and 4-pack prices were almost the same. The fact that gifted copies got the extra links too was more likely a mistake.

With the flood of Hammerwatch giveaways, I am wondering how long it will be before everyone has a copy?

Same here.

Mine have been appearing and disappearing more or less at random, haven't gifted any of the extras yet. Currently they're listed. Most likely we're dealing with some sort of a bug.

If you lost your extra URL's i may only mean that, you forgot where they are or something like that.

Go to the hb page, log in (top right corner). Then, click on your name, then My Library and clicking "Claim Past Purchases.".

You will receive every single link of every single purchase you made. If you really have extra URL's they will be there. If you STILL have trouble after this and you did not claimed those games, then contact humble bundle.