My assumption is no, it is simply a misperception.
So the experiment.
I need two things. Coffee and milk. Coffee is fresh ground Starbucks. The milk is cow squeezins. Since tweaking the tiny tits of an Almond for milk cramps my hands I'm going to use cow.
Now science is all about observation and measurement. I don't have any high fallutin thingamagigys so there is an understanding of inaccuracy. I attempted when and where I could to eliminate as many variables as possible. In the end, I think I did pretty good.
For the coffee:
Since temperature is a factor, this coffee maker is great. It has an insulated carafe. This means no hot plate changing the temp of the coffee. The carafe keeps the coffee stable.
The cups: Three exact porcelain cups. Heat absorption is going to be a big factor. This can change a lotta stuff.
The thermometer. Big importance. It too can heat up. Sticking a hot and or cold thermometer in the coffee can change the coffee. I could have used multiple thermometers, but they are not necessarily accurate to each other. I have in the past tested them and each one is a few degrees off from the other. So I decided to use one. I was careful to cool or heat the probe to a standard 73° prior to each use. Why 73? Random number really.
Also the measuring cup I used had to be 're-set' between each use. This was tougher and less accurate. I ran cold water on it between each use.
Milk was 48°. It was going to heat up so I had to control this with speed. Everything had to be done in seconds. So I was moving. As the experiment went on I added a smidge more milk to keep it at 48°-ish.
The control. First cup, 3/4 cup of coffee, no milk. Temp 159°.
Second cup, 3/4 cup of coffee with one tablespoon of milk. Temp 146°.
Third cup, one tablespoon of milk, 3/4 cup of coffee. Temp 145°
Resetting everything with cold water and repeating the experiment gave me:
The control. 158°
Second cup, 152°
Third cup, 150°
I was pleased with the results as my technique was working and I was getting faster. I also had to be careful not to let the thermometer probe touch the bottom of the cup. This sent numbers all over the place. Also the cups were heating up. Getting them back to room temp was tough.
Third and last test:
The control 158°
Second cup, 140°
Third cup, 144°
I think at this point my trying to 're-set' the cups with cool water was doing me in. I was also at this point out of coffee and everyone in the dinning room was grumbling that they wanted coffee so the experiment was over.
I had contemplated before that there was a cup factor, where the cup itself would heat up a little, cooling the coffee slightly, but then having the cup as a thermal 'battery' which stabilized the coffee so the milk didn't cool it off as much. When I did touch the bottom of the cup, the temp gauged spiked and depending on where on the bottom of the cup was important. There was more heat in the thicker areas of the cup.
I wanted to check the cups again in a few minutes to see it everything balanced out, but someone drank my experiment.
Now Todd can make the argument that he was right, however because the thermometer I used bounced back and forth a couple degrees, I would say that within a margin of error there was no appreciable difference.
Plus, assuming I was getting the cups back to room temp, the third showed a spike in the temp. Thinking of it now, using more cups would have been a better plan. I have a dozen of them. That would have been smarter. Lesson learned.
So, it is now up to Todd to replicate the experiment and post his findings. Because that is what science is all about.