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.
What if you are in a signature campaing tho? they remove you from the campaing if you don't use the same address every month, and you have to put it publicly in your bitcointalk profile. Is there any risk into any of this?