Yes several ones.
First there is the one from Apple. It´s called "Dateien Abgleichen" in german, I don´t know the english name (maybe "Adjusting/Aligning Files"?). It´s free at my OS 9 CD as option to install (maybe also 8.6?).
Than you could try Doublet Scan
http://www.hyperbolicsoftware.com/DoubletScan.html
And there was another shareware, I couldn´t find right now not even remember the name, … exactly for keeping folders synchronised.