Neither of these two domains exhibit much sign of a penalty
If they did, your domain most likely wouldn't show at the top, it would show at the bottom or not at all.
They don't seem to have a lot of authority. Lots of low authority sites linking to each other don't have much to pass on.
Also, duplicate content isn't necessarily a cause for a penalty.
SERP's rise and fall. One of my domains has fallen from #2 to =42 twice in the past 3 months for some keyphrases while all the time remaining #1 for one of the top ones.
The more activity in the index/search phrase group, the more likely you are to hop up and down, especially new sites which used to get a high ranking for a while. This is entirely subjective and open to much debate. Have a look for "Google Dance" for example.
I know some very big SEO's in the UK (some are notoriously blackhat). They build and test spam sites with up to 1,000 blogs, videos etc. I'm not agreeing with what they do but its interesting to note they are often able to stay below Google's radar for months, even years with tens of thousands of spam links.
I think you may just be panicking on this and I think you should stick to building a quality site and a quaity network.
Hope it helps.