Will the XBox Game Pass be automatically canceled when upgrading to ultimate? Since an Ultimate subscription includes this, or do I have to cancel the Game Pass and then subscribe to Ultimate to avoid paying twice?
You don't have to cancel it, it will be upgraded automatically.
Microsoft FAQ quote
What happens to my Xbox Live Gold or Xbox Game Pass membership if I upgrade to Xbox Game Pass Ultimate?
Purchasing Xbox Game Pass Ultimate will automatically upgrade your existing Xbox Live Gold or Xbox Game Pass memberships to Xbox Game Pass Ultimate.
About yes. It is actually "canceled" and converted for the remaining months. So if you still have 3 months of Gamepass, you get 2 months of Gamepass Ultimate, you suddenly have 5 months of Gamepass Ultimate. Microsoft simply converts the existing gamepass and "gives" you the remaining subscription of the other subscription. Example: I bought Xbox Live Gold for 45 euro at the end of April for 1 year, redeemed it and then got 1 month of Gamepass Ultimate on Xbox One for 13 euro. My membership consisted of 12 months of Xbox Live Gold and 1 month of Xbox Gamepass Ultimate, now 13 months of Gamepass Ultimate. So I got a game pass for 12 months and saved a little over 60 euro, because Ultimate costs 129 euro for 1 year.
