If you find that your PayPal checkout page isn't showing the logo that you've uploaded to DPD, there is a good chance that you've configured a Custom Payment Page in PayPal. Any settings that you have configured in your custom payment page in paypal will over-ride any settings that you configure in DPD.
This problem mostly occurs for vendors that use multiple stores with DPD; with DPD, you can configure mutliple stores per paypal account, but PayPal's settings will apply to all of your DPD stores. You can check your customized setting by logging into your PayPal account and going to:
My Account > Profile > look under Selling Preferences > Custom Payment Pages
You'll see a list of page templates. Click on the page style that is set to Primary and then clear out the fields Logo Image URL, Header Image URL, and save. Once done, Paypal should now display the logo's you've uploaded to DPD.