Odd mac addresses on switches

Have been having a weird issue here and there, we have ports locking out from strange addresses, when it happens it seems to be particular machines that have it. They are either invalid/nonsensical mac addresses, they dont seem to correspond to any actual devices but all seem to start with 00:00. If you do OUI lookups they either return random vendors or nothing. They're different every time.

Has anyone seen this? Not sure if I should care about this, or just set the port security to discard on those ports and go about my day.