I also bought the SYSTEM-8 last week from Plugin Boutique, but I have contacted Roland Cloud support and asked them if there is any possibility to swap/replace the currently owned SYSTEM-8 license with a license for XV-5080, which I don't own and has the same price as SYSTEM-8. Something conceptually similar to what I understand it is possible to do for the Keys obtained via Play 4 Life promotion, while the subscription is active.
At first they misunderstood my request and thought I wanted a refund so they told me to take it with Plugin Boutique instead, but after clarification they were really kind and removed the current SYSTEM-8 license from my account and added the XV-5080 instead. This way at least I avoid duplication.