I'm fairly confident the signature on the Michelstadt etching is Pieter or Dieter. But I couldn't find any other etchings under those names.
For what its worth the 't' in the handwriting in the word Marktbrunnen is kind of old school. Its like my dad's handwriting. He says that's how he learned to write it back in the early 40's. So I think we can safely say that one is early 20th C.