Please describe what you are doing to trigger the bug:
Downloaded duplicacy version 2.3.0
Change working directory to a repository
Execute a miss-spelled Duplicacy command, even with only a capitalized letter.
Duplicacy.exe List
(or any other duplicacy command word)
This fails because the syntax expects only lower case (which is OK of course!), but due to Duplicacy not returning an error, the user might not understand why the command fails. (Happened to me! 
)
Please describe what happens (the wrong behaviour):
Duplicacy returns exit code 0 (which by convention means no error)
and outputs No help topic for 'List'
which might not tell me that the word is spelt with wrong case.
(Linux users might be more used to this)
Mixed case in options (like -storage-name) returns exit code 2
Please describe what you expect to happen (but doesn’t):
If not accepting mixed case, I suggest to output an error message, something in the line of “Unknown command (must be lowercase)”, and exit with a non-zero exit code, for example exit code 2 which is already used for unknown options.
One could consider if commands and options could be case-insensitive.