La Juanda on Chess 1664 is different indeed

Recently a reader referred to my blog article on La Juanda - back here.
Again there rose a discussion about whether there are two variants of this song, or not: Is the version of this song on the original Chess single (Chess 1664) different from the version used on the LP albums (and all of the CDs)? When this question last came up in 2008 I had listened to those records over and over and did not hear any difference. In contrast others, especially Berry expert Morten Reff, insisted in hearing a difference. When this topic now came up once again, I decided to finally sort this out. So I grabbed the versions into audio files and used several computer programs to analyze possible differences.
Finally I stand corrected! Indeed there are differences in the single version of La Juanda versus to album and CD versions!
Both records obviously use the same basic take having the musical instruments and the main vocal. This results in both versions having the same length and sounding exactly the same.
However, as you will know, on this record Berry sings with himself in harmony. This was done by overdubbing a second background vocal track onto the original recording. And here is where the differences can be spotted. Either the engineers used a different second vocal track for the single or they modified the background vocal track before including it.
Fact is that there are a very few seconds in this song where you can hear the two versions differ. The most prominent part is during the first refrain where Berry switches from Spanish to English singing "I speak only the language of English" (close to 0:40 minutes in the song). In the single version this sentence is sung as a duet of Berry with himself having clearly two vocal tracks. In the LP version (e.g. on the Hip-O-Select box) the same sentence is not double-tracked. Here Berry clearly sings alone with a single voice.
My apologies to all those with better ears. I added a note to the Chess records section of this page.