First let me see if I have the issue right, you have two columns in the data result
User_Country and Page_Country. These both have Country Codes not the full names.
Now you have made a new source that has data for the Country code to its name.
You joined it once and see one column in your result of Country Name.
You do not need two spreed sheets.
All you need to do on the first join is rename the column to what you joined it to.
lets say on the first join you joined User_Country (the code) to the sheet to get the User_Country_Name so you should call it that.
Then join to the sheet by the Page_Country (code) to the sheet to have the Page_Country_Name and call it that.
In the end you should have four columns:
User_Country
Page_Country
User_Country_Name
Page_Country_Name
What it seams like to have done to me is only joined it once (hopefully in that one joined only said join on one column) so that why you are only getting one column for Country name. Join it two Separate time one for each Column you want to change code to name.