> ​If you have something like 2 pianos you can detune each one a few cents
> and get something sounds like 2 pianos (no matter how good the tuner is,
> he/she will never get them to be exactly the same).​

Hi Bob :)

We can already do that (always have been able to), but that is a fixed detune.
Play the same note repeatedly on the badly tuned 'piano' and it will be just as
badly tuned every time.

This idea doesn't really work with piano type instruments, as every time you
hit the same note it will be slightly different. It should work well with a
solo violin.