There was one at the Dallas Safari Club Convention this year.
It was in .375 H&H. Two single stack tandum magizines fed by a massive double faced bolt.

AN interesting piece of engineering. The bolt handle turned a large threaded locking collar. The bolt only moved back and forward. It did not rotate for obvious reasons. The action was very smooth.

This is not your light weight mountain rifle! I only fondled it for a short time, but I did not think it was well balanced?

A lot of money, a real big rifle!