Typically that slot is disabled on overflow, so that no more objects can be created at that slot / memory location, which avoids the handle collision. The slot could be recycled at specific points in the code when it is certain that no more handles for this slot are out in the wild (not sure if Vale does that)

(Or possibly the whole region could be discarded once it was running full, and the physical memory recycled at a new virtial address. There's plenty of virtual address space to burn through when not limited to 32 bits)