Simple paypal question

Hi I’m trying to upload a paypal plugin but am getting this message:

Destination folder already exists. /httpdocs/wp-content/plugins/WP-accept-paypal-payment/

This is failing the installation attempt, but I have deleted the folder from the FTP and deleted the plugin from wordpress and downloaded it afresh, but yet it says it already exists? I’m not sure how it can say that.

Please help.