Remote Desktop Connection Manager (RDCMan) app was discontinued last year due to an important severity information disclosure bug the company decided not to fix. RDCMan is a Windows RDP (Remote Desktop Protocol) client used by system admins to manage multiple remote desktop connections. After discontinuing the app, Microsoft advised customers to switch to Windows built-in Remote Desktop connection or universal Remote Desktop client. Microsoft has now added the app to the Windows Sysinternals toolkit and released version 2.8 in late June.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-revives-deprecated-rdcman-after-fixing-security-flaw/