Equality of ribbon numbers for symmetric ribbon knots of ribbon number two

Let $K$ be a symmetric ribbon knot. Its ribbon number $r(K)$ is the minimum number of ribbon singularities in any ribbon disk bounded by $K$, and its symmetric ribbon number $r_s(K)$ is the minimum number of ribbon singularities in any symmetric ribbon disk bounded by $K$.

Ribbon-number-two conjecture. If $r(K)=2$, then

$$r_s(K)=2.$$

All examples in the authors' data with $r_s(K)>r(K)$ have $r(K)\geq 3$, so the conjecture isolates the first case in which the two invariants might necessarily agree.