Hi
I'll try to explain what each of your stmts does:

 my ($mkt,$pass) = split;
assign first word of line (user or whatever that is) to $mkt
and Password (second word of line) to $pass

$passwds{$mkt} = $pass;
assign Password to hash/key %passwds/$mkt
assign User to hash/key %passwds/$pass
At the end you got a hash with every User _AND_ every Password as key. The values contain vice versa the Passwords and the Users.
Now it's impossible to have just a list of the Passwords because you cannot distict them anymore.

just do:
$passwds{$mkt} = $pass; in your loop and then you can get all Users or all Passwords like that:

@listOfPass = (values %passwds);
@listOfUsers = (keys %passwds);
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Imre

PS
close if stmt with } before accessing the whole list ...