You can set up your value list to have two columns of data. Column 1 is your ID field and column 2 is the name field you need to know which item to choose to assign the correct role.
Open Manage | Value Lists
Create a new value list and select the "Use Values from Field option". You'll see two side by side boxes for specifying values in these two columns. In column 1, you can select RoleID from the Role table. In column 2, you can select Title from this same table to show the name of the role.
That's all you have to do. You can hide the RoleID column if you wish, but don't do this unless you know the value in Title is unique for every Role ID (there's a validation rule you can set to make sure this happens). Otherwise, the duplicates will disappear from your value list and you won't be able to select subsequent duplicated values.