Chuck Berry at Baarn

Chuck Berry where?
Baarn is a small town in the Netherlands, not far away from Hilversum. I do not know if Berry ever played a concert in Baarn and I strongly doubt so. But this article is in the Chuck Berry Rarities category, not in Chuck Berry Live Tapes. So this article is not about a concert, it is about rare records and stuff.
What makes Baarn interesting is that in the early 1950s Philips built their first LP pressing plant here. Since then Baarn has always been related to records and recording, even today Universal Music has their Dutch office in Baarn.
The pressing plant changed names over the years as the music business of Philips became Phonogram, later Polygram. In the 1970s Polygram also produced the Chess label records for distribution in the Netherlands, Germany, and other parts of Europe.
Recently a seller on ebay sold some interesting items related to Baarn. He said his father worked in the pressing plant and took home some souvenirs. So I was able to purchase an unused label of the Chuck Berry's Greatest Hits album (Chess 9283 004).

Of course this is just a gimmick, but it's certainly something not seen often.
Even rarer is another item I recently was able to purchase from a different source. It is also Dutch and I pretty much believe it stems from the Baarn pressing plant as well. Below is a record which label says "Proefpersing", i.e. Check Pressing. The number is CH 50043 which is the US catalog number of Chuck Berry's Bio album of 1973. From the label we can see that this test pressing of Bio was made or checked on September 25, 1973. Both A and B side were checked and approved. The print and signatures are on side A only. Side B has a completely blank white label. An interesting question is how such an internal test sample somehow made it to the record collectors market. Do you know of other, similar items?