Hi Tracyp,
I believe those mags are fabrications. I have a 1939 in the z block with 2 matching mags. On the auction mags, the style of the numbers and the suffix doesn't appear to be correct and the spare mag should have a "+" on it. I'm not sure about the tubes as there was considerable overlap between the use of the formed sheet metal mags and the extruded mags. I would guess the tubes could be correct for the period but I believe you are correct about the P08 showing up later. Here is a link to my web site showing my spare mag for comparison.
http://lmd-militaria.com/page23.html
Regards, Leon