In case anyone else finds this thread and has the same question:
I can confirm that the msrdc and msrdcw executables are for the installed program that resides in C:\Program Files\Remote Desktop
The RdClient.Windows.exe executable I believe is linked to the Microsoft store app which is fundamentally a different program packaged differently and therefore has a different version number.
Last time I tested, the store app was lacking in a number of key respects including the ability to sign in to multiple accounts, and some multi-monitor support as well I believe. This may have been fixed by now, I've just defaulted to the downloaded and installed program ever since.