[Nabeshin]

If I already SEed amazon with one account, and I want to SE with another account but in the same device (notebook), can they see that this is the same device? Am i need to buy another device?

Yes, Amazon can detect multi-accounting with the device In use.

If you don't have another one, use an RDP.

This is a GOLD advise. Do you think a Virtual Machine like ubuntu or similar could work? Or they still can see that it is the same device?

You'd have the same IP but that's about it, I don't think it's enough to mark a multi-account since an IP can and will be shared in multiple cases (internet cafè, dorms, offices and so on)