If two or more slashes are used when running the /alias command from the command line, (or if the /alias command is run from a script), it will run silently. Compare:

Code:
/alias test1 noop


to

Code:
//alias test2 noop


The first prints * Added 'test1' alias, while the second doesn't print anything. The same behavior occurs, of course, when removing aliases via //alias.