Depends on uncertainty and initial conditions.
I assume there are 3 possible outcomes:
robot A wins
robot B wins
a tie
Outcomes:
1.With perfectly balanced initial conditions, and no uncertainty, it will always be a tie. (If there can be no tie, then the win conditions will never be met)
2.With unbalanced initial conditions, and no uncertainty, there will always be the same winner.
3.With perfectly balanced initial conditions, and some amount of uncertainty, it will be statistically similar. (So in 100 games each should win roughly the same number of times.)
4.With unbalanced initial conditions, and an amount of uncertainty, the outcome will be dependant on the initial conditions and will be statistical in nature.
TLDR;
However, with enough uncertainty it's always going to be a statistical answer.
Physical (real) robots? Fighting hand-to-hand? Identical models in a enclosed arena?
50/50; flip a coin.