Most commands autocompletion infinitely propose arguments. When in most cases, the arguments should be only proposed when they're at position argv[1].

Example:

phpsploit> exit

This command has an unique '--force' argument.
If user presses multiple times, he ends up with a command looking like that:

exit --force --force --force --force --force --force

completion arguments should be proposed only when they are on the expected position.