With that being said this does look exactly like what a TX will look like when you receive bitcoin from bitmixer.
I've not looked at bitmixer transactions, but that isn't what I'd expect transactions from a good mixing service to look like.
Have you seen other similar transactions that you knew were not from a mixing service?
Almost every transaction that I ever send from Bitcoin Core looks like this.
a good number (probably most) addresses tend to collect multiple inputs that are somewhat smaller then the total "balance" in an address.
This is true of everybody that fails to use a new address for every transaction. I choose to do as recommended by Satoshi so I almost never have multiple outputs at the same address.