Let $(\Omega, \mathcal{F}, \mathbb{P})$ be a complete probability space and $(X,\mathcal{A})$ and $(Y,\mathcal{B})$ be measurable spaces.
Consider a $\mathcal{F}\otimes \mathcal{A}–\mathcal{B}$-measurable function $f\colon \Omega\times X\to Y$ (call such functions jointly measurable).
Let $g$ be another function $\Omega\times X\to Y$, but let $g$ only be measurable in the following sense to begin with: For all $x\in X$ the position $(\omega\mapsto g(\omega, x)$ is $\mathcal{F}-\mathcal{B}$-measurable.
Now, does it follow from the indistinguishability of $f$ and $g$, i.e. $$f(\omega, x) = g(\omega, x),\quad x\in X$$ for almost all $\omega\in\Omega$, that $g$ is jointly measurable as well?