It sounds like a spun bearing for sure. My BMW M3 began to make a similar noise like that so I took it to the dealer. They did not go too deep into it and replaced the VANOS unit in the car and didn't notice anything funny after replacing it. After I got it back, it made the same clunking noise at low RPMs, so I drove it normally for the next few hundred miles, thinking the sound was ok. At one point the bearing finally blew out and ruined the crankshaft and the engine sounded like an old Mercedes diesel. It turned out that the bearing had blew and the engine needed to be replaced.
I would get it checked out for sure. Good luck. Hopefully the same thing that happened for me isn't happening to you even though they are two separate cars.