Testing Hub collisions

[ZeonOtaku]

I'm testing two ethernet-to-coax (think television coax, not that used in 10BASE2) adapters. I'm just curious if these are more like hubs or switches. Anybody know of a way to intentionally cause hubs to collide? I had some powerline ethernet adapters (running ethernet over 110VAC) years ago, and when I tried to run two Xboxes over the same hub, one couldn't connect, so I could only assume this was a collsion at the time, though not like I can bring two Xboxes into work.