One method, (there may be others) is to use sub-selects:
```sql
select
Support.main as MainKey,
( select Name from Names where Names.Key = Support.Main ) as MainName,
Support.Backup as BackKey,
( select Name from Names where Names.Key = Support.Backup) as BackName
from Support ;
MainKey MainName BackKey BackName
---------- ---------- ---------- ----------
10 Bob 72 Sally
106 Amanda 73 Jose
```
For symmetry, I've used sub-select for both names; you could leave the `JOIN` in place for one of the names and use a sub-select for the other.