Same Address, Three Separator Conventions — and Two Meaningful Bits
A MAC address is a 48-bit hardware identifier, and colon, hyphen, and Cisco-dot notations are purely different separator conventions for writing the identical 48-bit value — converting between them changes nothing about the underlying address (see MAC Address Format Guide for the full breakdown). What actually carries meaning are two specific bits buried in the first byte: the unicast/multicast bit and the universally/locally administered bit.
The locally-administered bit specifically is worth knowing how to read: when set, it signals the address was assigned by software (a virtual machine, a container, or a device's MAC-randomization privacy feature) rather than burned into hardware from a manufacturer's registered OUI block — a quick, useful signal for distinguishing a virtual or randomized address from a genuine hardware NIC's original address during network troubleshooting.
Generating random test addresses deliberately sets this locally-administered bit correctly, which matters for realistic testing — a properly-formed random test MAC should be recognizably "locally administered" by design, not accidentally colliding with a real vendor's registered address space.