" abmachen (German) can mean "to arrange" or "to agree on" something, especially a meeting or an appointment. It can also mean "to take off" or "to remove" something.
(do)ujednat (Czech) means "to arrange" or "to negotiate" something, often an agreement or a deal.
So, in the context of arranging a meeting or making an agreement, "abmachen" and "(do)ujednat" are indeed very close in meaning.
For example:
"Wir haben abgemacht, uns morgen zu treffen." (German) – "We agreed to meet tomorrow."
"Dojednali jsme si schůzku na zítra." (Czech) – "We arranged a meeting for tomorrow.""
