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VNL is completely a clone of Libcoin.You can check the source code by yourself.
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Why do you say that? I did some quick comparisons of the latest github source trees and there is some similarity, but it's certainly not a simple clone. It looks like a reimplementation based on some of the structure of the standard bitcoin daemon and Libcoin. Seems like he put quite a lot of work into it.
I used Peercoin as the reference implementation and nothing else. If you cannot tell from the source code that this was a massive effort I cannot help you.

Thank you for your support.