Yes, Holst did record The Planets twice...
It's completely serendipitous that I just more or less finished a
restoration (strictly for my own amusement) of the 1922/23/24 acoustical
version of The Planets, with my usual improvement in bass response, along
with other improvements. There are so darned many little thumps on these
discs that I so far haven't had the patience to remove them all, and
that's why I say "more or less" above.
Having just done this and having tried my own hand on the 1926
electrical, I can at least say something about both performances. The
acoustical Venus is about 50 seconds longer than the electrical one, and
the added relaxed feel is very noticeable. On the other hand, the "big
tune" from Jupiter begins much too quickly on the acoustical recording.
On both recordings, the "big tune" is split over two sides, and, in the
case of the electrical recording, the tempo is consistent from the first
side to the second. In the case of the acoustical recording, the already
too-quick tempo suddenly has the brakes put on it at the end of the side,
with the final note at the end of the side badly distended. When the
second side begins, Holst uses a more moderate tempo similar to that on
the electrical recording. Other than these two major differences, I find
both performances quite similar!
Incidentally, unless I'm hearing things incorrectly, it appears that
several of the cymbal clashes were eliminated from even the electrical
recording (!), as is also the case on the acoustical recording. There
seems to be precious little above 5 kHz on the electrical recording,
whereas the acoustical recording seems to go at least up to 3.5 kHz.
One can't complain that Holst rushed the tempi due to side length, since
in almost all cases there are no sides which exceed 3:30 in duration
(the most notable exception being the acoustical Venus, which has a side
slightly exceeding 4 minutes). The second side of Neptune is only 2:20!.
Frankly I prefer the swift tempi compared to the more common lumbering
tempi of today. Roy Goodman had a period instruments recording of The
Planets on Carlton for a while, and his tempi emulated those of Holst,
with the exception of Neptune, where he takes nearly a minute longer than
Holst to get through it. I think it is one of the best performances I've
heard in decent sound. These quicker tempi are most likely authentic.
Albert Coates, who gave the public premiere of The Planets, recorded
Mars, Mercury, Jupiter, and Uranus in 1926, and Mars, in particular,
seems to leave Holst behind in the dust. It actually isn't that much
faster; it's just that the orchestra couldn't keep up with Coates.