We provide some existence results for Sturm-Liouville boundary value problems associated with the planar differential system $Jz'=g(t,z) + r(t,z)$ where $g$ is suitably controlled by the gradient of two positively homogeneous functions of degree 2 and $r$ is sublinear with respect to the variable $z$ at infinity. We study the existence of solutions when a double resonance phenomenon occurs by the introduction of Landesman-Lazer type conditions. Applications to scalar second order differential equations are given.