Rule Move but copies POP mail

Anyone who setups a rule to move mail from there inbox to a folder ends up with a linked copy not a move. In other words i setup a rule that says any mail coming from @dell.com move to folder Dell. say i get an email from johnsmith@dell.com it shows up in my inbox and my dell folder as unread. If i delete it from either folder the message is deleted in both places. All our rules for interenal mail work just fine. i haven’t tested other rules just move but it does this with any move i set coming from POP internet mail.