I am an inexperienced user of Unity who is attempting to complete a project begun by someone else with Unity 2017.3.f03, and I am continuing to develop with that version. It makes use of Vuforia and involves acquiring a standard 2D target image. A problem has abruptly appeared that I was not having previously. When I play the project and present an appropriate target image to lock onto, several graphics appear as I expect them to in response to this event. However, one of them gets "stuck" in the sense that instances of it stack up on top of each other apparently ad infinitum instead of it's appearing just once as I expect. Has anyone else experienced similar behavior?