Installation guide and your website Adobe Premiere Elements Help | Install Premiere Elements says that serial number will have 1057 as first 4 digits; that is for Photoshop elements, not for Premiere elements which has 1st 4 digits in my package of 1143. You obviously cannot correct printed and shipped material, but should correct the website. The 1143 is apparently correct; installation worked.
This is not Adobe. Rather essentially user to user forum. The frequency of appearance of Adobe in this Adobe Premiere Elements Forum is not defined.
For at least current version 13/13.1 as well as 12/12.1, 11, and 10, you appear to be correct in your observation.
Just in case mention...you need to use the serial number that comes with your specific purchase. To date, there has been no Adobe notification to override any part of the user's serial number as seen on the label of the purchased product.
You could file an Adobe Feature Request Bug Report Form to call Adobe's attention to this misprint.
But, a new version of Premiere Elements is expected to be released by Adobe in September October 2015. At that time, many Adobe documents are expected to be updated or to disappear.