Or how it should sound?
Here is the situation in my iTunes library:
The same song, but different times and bpm. So it must be three different versions, right?
Wrong. It is the same version. If I process the files to have the same playing time, they play in perfect unison. Every note and every nuance is exactly the same. Also, according to Brian Rust, the California Ramblers only recorded this song once. (Golden Gate Orchestra is a pseudonym for the California Ramblers. This also shows the problem with accurate labeling of digital music.)
So, what happened? Carelessness. Music from the swing era and before is only preserved on records. The master recordings that these records were made from are long gone. No seems to have thought about preserving them, and it is probable that companies did not want to spend the money to store them. Those that were saved were recycled to provide material for World War II.
When you buy this old music in any digital format, what you are buying is music that someone digitized from an old record. This is true of all music recorded before WWII. In most cases, this work is done by record collectors, not by a big record company or an archive. There is a real art to getting the best sound from these records. Some are good at it, and some are not.
Unfortunately, many transfers are not done to the highest standards. The proof is the fact that many of these transfers are not played at the correct speed; this is the easiest part to get right. This song is glaring evidence of that, but I have many, many songs with subtler problems. You notice the problem when you have two copies of a song with slightly different pitch, or when you try to play your instrument along with an old recording and you can't. It is fairly common that these transferred recordings are out-of-tune or are in a key like B natural that no jazz band would have played in. Even if this were the fault of the original record, it is simple to correct in the transfer process.
So, this is a warning that not all copies are the same. If you find a song you love but the sound is poor, keep looking. There may be another transfer with better quality. If the tempo sounds unnaturally draggy or frantic, it may just be wrong. We should be very thankful that all of these collectors have gone to the incredible effort of preserving this music and making it available to us. But we should be aware that the quality of the digital transfers varies greatly.