If both horses are ranked first for a factor then yes - you can use min gap.
Example, you want to flag the top JPR horse in the race but avoid cases where two or more horses are tied for the top JPR.
In the UDM Wizard:
1. Set both min and max JPR rank = 1.
2. Set min gap to .01 and hit Save.
The second constraint will prevent the UDM from flagging horses in races where the top two JPR horses are tied with exactly the same JPR.
Now, if you're looking to avoid cases where you are dealing with two or more horses tied for say fourth best in the race for a given factor then no. That's not something I've ever thought to address.