If you look more closely, I expect that what you will see is that the kg is really kp for kiloponds. A thousand kiloponds is slightly less than a thousand bar.

My Arrietta 601 was proofed in 1982 for 1200 kp which is about 1768.798 Bar.

Spain followed Germany in the use of kiloponds and continued even after Germany switched to kilograms and then to Bar to prevent confusion between weight and pressure.

I think that Spain went to Bar in 1987.

danc