Fix inconsistent lighting in GLES2

Issue was possibily being caused by duplicating a light even when that
light was not in the render_light_instances array.

drivers/gles2/rasterizer_scene_gles2.cpp

@@ -1133,8 +1133,8 @@ void RasterizerSceneGLES2::_add_geometry_with_material(RasterizerStorageGLES2::G
 
 				LightInstance *li = light_instance_owner.getornull(e->instance->light_instances[i]);
 
-				if (li->light_index >= render_light_instance_count) {
-					continue; // too many
+				if (li->light_index >= render_light_instance_count || render_light_instances[li->light_index] != li) {
+					continue; // too many or light_index did not correspond to the light instances to be rendered
 				}
 
 				if (copy) {