Second hot break!

I just put an extract batch of Yooper's Dead Guy Ale clone in the sink to cool and had a question. I tried a late addition of half of the DME the recipe called for (8 pound total - so I did 4 at the beginning and added the other four with 10 minutes left). It took a while to add the last 4 pound because it kept foaming up. Probably added 15 minutes to the boil. It appeared to undergo a second hot break. Does this actually happen? I did a late addition with LME once and didn't have this happen. What gives? I don't think the extra boil time will hurt, but I was just wondering.

Thanks in advance.

The extra 15 minutes of boil would increase your hop utilization. So the beer may be a little more bitter than it would otherwise have been.

I guess it is reasonable for the second addition of extract to go through a hot break if it is being boiled. One thing you might want to consider is adding the second addition at knock out. Just add the extract at the very end when the boil is complete. Then let the batch set for 10 minutes or so before cooling. That 10 minutes will be sufficient to kill anything that might affect your beer, even if it is not boiled. The wort will be sufficiently hot during that period to do the job.

I thought about that, but if it did go through a second break, does that mean that it needs to? Would there be any "harm" if it didn't break?

Extract has already undergone its hot break when it was produced. It does tend to foam up a bit when you add it to the boil (DME more so than LME), but I am not convinced that this is an actual hot break as it happens with grain-based beers. So I wouldn't worry about it - either way is fine.