According to Mark Lloyd :
I have one 12VDC 1A power supply that is connected to 2 separate
cameras. This is a regulated supply, which was needed to reduce noise
in the video output of the cameras.

If one of them needed a different voltage, it would be possible to use
diodes (consider current here too, diodes have current as well as
voltage ratings) to drop the voltage (2 diodes in series give about
1.5V drop). If the devices have a common ground (as those cameras do),
that needs to be considered when powering multiple devices with 1
adapter.

Diodes in series is a reasonable regulator, but it might not
be good enough if the current through them varies a lot.

In which case, something like a three lead regulator would be
better. But, they usually need more than 1.2V of headroom to
operate.

[That was what I was envisaging for my "universal wallwart strip".
A series of jacks at, say, 20VAC, with things that plug in that have
combinations of bridge rectifiers and regulator chips.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.