I think you may want to do some research yourself, or at least provide much better photographs. It may help to be able to read German, to unravel this mystery.

Altinger seems to be a custom maker of racing bikes from the 80s and 90s and maybe earlier. I looked at a few of the bikes on that website, they don't look like the two bikes you are showing.

Sigi Renz was a bike racer in the 60s and 70s and it seems he sold and perhaps made some bikes too. You can google up images of those and compare.

I can't read much about these two people since the sources are in German.

As for your bikes, they look like production bikes, not custom, and I imagine someone familiar with smaller European brands could easily identify them from the "S" marks on seatstay and fork crown.