Multiple licenses with one email address?

Can I buy multiple licenses associated with one single email address? The reason I’d like to confirm this is because I already have valid licenses for DTPO - I’d like to know if it’d be fine if I use the same email address to buy additional licenses.

P.S.: I do understand that ordering multiple copies in a single order is possible.

Yes, this is possible without any problem. Successive orders are unified after they’ve been added to the database.