correct me if im wrong on this as im just guessing here
$test_two($1,$2) will be identified into the command true
which doesnt excist.. try it with /test_two($1,$2)
that well fail as well
TEST_TWO($1,$2) Unknown command
you cant bracket the parameters if issuing as a command. It sees "TEST_TWO($1,$2)" as one big command name.
But you are right about it being identified into the command true.