Essentially, it’s just another word for multi-homing a device (such as a server), with the caveat that it’s done on the same link rather than separate links. It’s generally a bad practice because multi-homing mostly accomplishes 2 things:
1. It wastes IP addresses needlessly (in most cases)
2. It creates a layer 2 security risk because you now have direct paths on multiple networks with typically no filtering (because most environments filter layer 3 but not layer 2), and because if anyone breaches that host they can now easily move laterally across the rest of the hosts on the same networks.