Heyy, ChipMixer, long time no see! 
That being said, I also experienced address reuse, which I suppose is a realized decision by the OP.
I hope this does not violate the rules, because this is not a Bitcoin Mixer that can be truly used.
It does not violate any rule. It is forbidden to direct people to Bitcoin mixers, but this one does not even have to do with real bitcoin. You're just playing with testnet.I understand the Nostalgia regarding the once great mixer, but what do you intend to achieve with this?
If you think about it, there is no easy way to mix testnet bitcoins. You may be wondering why would one want privacy in testnet, but I'm sure there is a reason or two. For example, you might not want to reveal you own a faucet. That is a feedback for the project too. That being said, I also experienced address reuse, which I suppose is a realized decision by the OP.