In the example of two 0.0015 deposits, both are above the minimum chip size. In your example, the second deposit is below the minimum chip size and is therefore treated as a donation.
you misunderstood the example in the faq,
the minimum amount per deposit (1mbtc) is still intact
the minimum amount rule applies to each deposit (utxo), NOT total amount of deposit
that statement gives an example condition of 2 deposits over 1mbtc each
the example simply explains that you won't lose the fraction if they sum up to a full mbtc
I'd agree that the current example is a little confusing... and can certainly understand why you thought it would work that way. I think the ChipMixer admins should tidy that FAQ section up a little to make it a bit more obvious.
@TheQuin, @Thirdspace, @HCP,
My adblocker had nix'd your sigs so looking back through the thread it looks like you guys might be ChipMixer admins. My apologies for not realizing it earlier. I was looking for an official response and here were many. Anyway, I get the layout and now follow the intent of the FAQ. Thanks to all for helping straighten it out. Overall been pleased with the service. Been using the onion so didn't get hit with the SSL hickup earlier. Thanks for providing Tor access BTW.