I can name the portal and say go to object but isn't that the exact same thing as go to field with in the portal?
No it is not, as the name is added to the layout object (which happens to be a portal here) via the name box in the inspector.
That said, go to field Should put the focus on the correct portal, if the field specified only appears in that one portal. If the same field exists in both portals or is located somewhere else on the layout, you may get the focus in a different copy of the same field.
Also, an OnObjectEnter script trigger could be tripped by your go to field step and this could change the focus to somwhere else on your layout. Depending on where your focus is when the script is performed, other triggers on your layout might be tripped by your script.
If you name the portal object as 'MyPortal', and you have a script that is:
Go To Object ["MyPortal"]
Go to portal row [First]
are you saying that it doesn't stop at the first row of the correct portal?