Correction to: Curvature growth of some 4-dimensional gradient Ricci soliton singularity models

Abstract: This note corrects an error in the proof of Proposition 13 in arXiv:1903.09181 and simultaneously establishes a more general result. We prove that if $M$ is a compact 4-manifold with boundary $\partial M$ a rational homology 3-sphere, and if an unbounded number of disjoint copies of $M$ embed in a compact 4-manifold $N$, then $H_1(\partial M;\mathbb{Z})$ is a direct double. This partially generalizes a theorem of Hantzsche in the case of rational homology 3-spheres.