Sherman Hill Locomotives Have Two Entries?

I notice when selecting a timetable on Sherman Hill there seem to be two entries for the SD70Ace and SD40-2. One with UP before the designation and one with it after.




It doesn't seem to matter which you pick. Is there a reason for having two entries or is it just an error?

DW

 

Different horns.

 

You're kidding me, they sound the same to me.

DW

 

There are very slight differences. Unless you know the nuances of every horn, it's going to sound basically the same