This paper by <PERSON> et al. suggests that the answer to your question is "no": arxiv.org/abs/1104.2851v2. <PERSON> et al. consider the weak-field limit of $f(R)$ gravity where matter that contributes to spacetime curvature is assumed to be non-relativistic (<PERSON> et al. say at one point that they are assuming the spacetime is stationary. But this is not necessary; it is only necessary to assume that the matter contributing to the stress-energy tensor has velocities small compared to c). These assumptions should provide a good approximation for clusters and cluster collisions including the Bullet Cluster which has an impact velocity of "only" about 1% of the speed of light (see arxiv.org/abs/1307.0982).
The field equation resulting from varying the metric in the $f(R)$ action involves $f(R)$ and $f'(R)$. <PERSON> et al. 469
assume that $f(R)$ in analytic in $R$ at $R=0$ so that in the weak field limit $$f(R) \approx f(0) + f'(0)R$$ and $$f'(R) \approx f'(0) + f''(0)R.$$ <PERSON> et al. show that in the weak-field limit the metric is given by (setting $G=c=1$) $$ds^2 = -(1-h_{00})dt^2 + \delta_{ij}(1 + h)dx^idx^j$$ where $$h_{00}({\bf x},t) = -2\Bigl(\Phi({\bf x},t) + \frac{1}{3}\Psi({\bf x},t)\Bigr),$$ $$h({\bf x},t) = -2\Bigl(\Phi({\bf x},t) - \frac{1}{3}\Psi({\bf x},t)\Bigr),$$ $\Phi({\bf x},t)$ is the Newtonian potential given by $$\Phi({\bf x},t) = -\int\frac{\rho({\bf x}',t)}{|{\bf x} - {\bf x}'|}d^3x',$$ and $\Psi({\bf x},t)$ is a "massive" scalar field given by the Yukawa form $$\Psi({\bf x},t) = -\int\frac{\rho({\bf x}',t)}{|{\bf x} - {\bf x}'|}e^{-a|{\bf x} - {\bf x}'|} d^3x'$$ where $$a^2 = \frac{f'(0)}{3f''(0)}.$$
$\Psi({\bf x},t)$ is the effectively massive scalar mode contained in $f(R)$ theories that is not contained in general relativity. The motion of a massive, non-relativistic particle is determined in terms of $h_{00}$ which depends on the additional scalar field $\Psi({\bf x},t)$. However, the motion of massless particles (e.g., photons) is determined by the combination $h_{00} + h$ which according to the above equations is independent of $\Psi({\bf x},t)$. <PERSON> et al. show that the motion of photons depends only on $h_{00} + h$ in the weak-field limit by calculating an effective refractive index. This is done by noting that according to classical geometric optics the trajectory of a photon extemizes the quantity $t = \int n dl$ where $n$ is the refractive index and $l$ is a spatial length along the path of the photon. The above metric implies that along a null geodesic $$dt^2 = \frac{1+h}{1-h_{00}}dl^2 \approx (1 + h + h_{00})dl^2$$ and therefore in the weak-field limit the effective refractive index is $$n = 1 + \frac{1}{2} (h + h_{00}).$$ Since this does not depend on $\Psi({\bf x},t)$, gravitational lensing is not affected by $\Psi({\bf x},t)$ in the weak-field limit and is given by the standard general relativity result in this limit.
The deflection of light can also be determined using the geodesic equation. This is done by <PERSON> and <PERSON>: arxiv. 281