If you are creating multiple user accounts on the same PC, each respective user profile will have it's own cookies, LSO's, and other stored data associated with your browser. From the concept of keeping your eBay and PayPal accounts separate this is important. Of course, you are going to need a separate IP address for each account also.
if you open a new user account on your pc, does it then show up as from a separate device?
Read's as a different machine ebay's end (Along with other sites) don't forget about router settings/resetting or perhaps using a dedicated VPN there are pros and cons with the VPN route i found but other members may have a different experience with them.